In Dependent Co-Arising, is Dukkha a Sankhara, a Vedana, both, or none? How should I understand dukkha (in all its amplitude and semantic complexity), if I want to see it through the lens of Dependent Co-Arising?

Where is it classified, apart from the final nidana?

Is it a sankhara? Is always something felt and, therefore, a feeling?

If dukkha is always something to be felt (as vedana), then does that mean that everytime the chain of conditionality gives rise to the final nidana, the chain "starts again" in vedana?

Thanks in advance for your time.

Kind regards!
Plenty of other things than vedana are dukkha, so you cannot say that dukkha is just vedana.

The buddha says that whatever is anicca is dukkha, so the way to find dukkha is to find something anicca, and all the stuff in Dependent Co-Arising are anicca.

the buddha says that this is to be known about dukkha:


  "'Stress should be known. The cause by which stress comes into play
  should be known. The diversity in stress should be known. The result
  of stress should be known. The cessation of stress should be known.
  The path of practice for the cessation of stress should be known.'
  Thus it has been said. In reference to what was it said?
  
  Birth is stress, aging is stress, death is stress; sorrow,
  lamentation, pain, distress, &amp; despair are stress; association with
  the unbeloved is stress; separation from the loved is stress; not
  getting what is wanted is stress. In short, the five
  clinging-aggregates are stress.
  
  "And what is the cause by which stress comes into play? Craving is the
  cause by which stress comes into play.
  
  "And what is the diversity in stress? There is major stress &amp; minor,
  slowly fading &amp; quickly fading. This is called the diversity in
  stress.
  
  "And what is the result of stress? There are some cases in which a
  person overcome with pain, his mind exhausted, grieves, mourns,
  laments, beats his breast, &amp; becomes bewildered. Or one overcome with
  pain, his mind exhausted, comes to search outside, 'Who knows a way or
  two to stop this pain?' I tell you, monks, that stress results either
  in bewilderment or in search. This is called the result of stress.
  
  "And what is the cessation of stress? From the cessation of craving is
  the cessation of stress; and just this noble eightfold path — right
  view, right resolve, right speech, right action, right livelihood,
  right effort, right mindfulness, right concentration — is the path of
  practice leading to the cessation of stress.
  
  "Now when a disciple of the noble ones discerns stress in this way,
  the cause by which stress comes into play in this way, the diversity
  of stress in this way, the result of stress in this way, the cessation
  of stress in this way, &amp; the path of practice leading to the cessation
  of stress in this way, then he discerns this penetrative holy life as
  the cessation of stress.
  
  "'Stress should be known. The cause by which stress comes into play...
  The diversity in stress... The result of stress... The cessation of
  stress... The path of practice for the cessation of stress should be
  known.' Thus it was said, and in reference to this was it said.


https://www.accesstoinsight.org/tipitaka/an/an06/an06.063.than.html

As usual dukkha arises from craving   and ceases from the cessation from craving like that


  “One who craves for and delights in bodily form, craves for and
  delights in dukkha. One who craves for and delights in dukkha will not
  attain liberation from dukkha. In the same way one who craves for and
  delights in feeling … perception … formations … consciousness, craves
  for and delights in dukkha. One who craves for and delights in dukkha
  will not attain liberation from dukkha.


https://suttacentral.net/sa7/en/analayo

If you want to find dukkha, just make craving arise and puthujjanas already crave and delight so it won't be hard to find dukkha.

So when there is no delight, this happens


  "There are ideas cognizable via the intellect — agreeable, pleasing,
  charming, endearing, fostering desire, enticing. If a monk does not
  relish them, welcome them, or remain fastened to them, then in him —
  not relishing them, not welcoming them, not remaining fastened to them
  — there arises no delight. From the cessation of delight, I tell you,
  comes the cessation of suffering and stress. {By this means, Punna,
  you are not far from this doctrine and discipline."
  
  At that time the Blessed One said to the monks: “You should rightly
  examine the eye as impermanent. One who examines it like this is
  called ‘with right view’. Because of rightly contemplating it,
  disenchantment arises. Because of the arising of disenchantment, one
  is free from delight and free from lust. Because of being free from
  delight and lust, I say the mind is rightly liberated.
  
  “In the same way [one should rightly examine] the ear … the nose … the
  tongue … the body … the mind … [up to] … one is free from delight and
  free from lust. Monks, because of being free from delight and lust, I
  say the mind is rightly liberated.


https://suttacentral.net/sa188/en/analayo

And the way to not have delight is this:


  “In the same way you should give right attention to feeling …
  perception … formations … consciousness, contemplating consciousness
  as impermanent, knowing it as it really is. Why is that? One who gives
  right attention to consciousness, who contemplates consciousness as
  impermanent and knows it as it really is, will eradicate desire and
  lust in regard to consciousness. One who eradicates desire and lust in
  regard to consciousness, I say, liberates the mind.


https://suttacentral.net/sa2/en/analayo

which is done with ''diligence''


  “To a type of monks like this I say that they [should] cultivate
  diligence. Why is that? As such a monk trains in the faculties and
  delights the mind accordingly, is endowed with the necessities of
  life, and associates with good friends, he will soon attain the
  destruction of the influxes, the influx-free liberation of the mind
  and liberation by wisdom, knowing here and now for himself and
  realizing that: ‘Birth for me has been eradicated, the holy life has
  been established, what had to be done has been done, I myself know
  that there will be no receiving of any further existence.’
  
  “Why is that? In relation to forms cognized by the eye which he could
  crave for with delight and become defiled by attachment, on having
  seen them that monk does not delight in them, does not praise them, is
  not defiled by them, and is not established in the bondage of
  attachment. As he does not delight in them, not praise them, is not
  defiled by them, and is not established in [the bondage of]
  attachment, he diligently progresses in the appeasing of body and
  mind.
  
  “With the mind fully established in peace without forgetfulness,
  always concentrated and single-minded, with boundless joy in the
  Dharma, but still attaining the foremost concentrative attainment, he
  will certainly not regress by following a form with the eye. In
  relation to [sounds cognized by] the ear … [odours cognized by] the
  nose … [flavours cognized by] the tongue … [tangibles cognized by] the
  body … mind-objects cognized by the mind it is also like this.”


https://suttacentral.net/sa212/en/analayo