Cannot shift into lowest gear I've been fiddling with my rear derailleur trying to fine tune it, because I just replaced my entire drivetrain (same components, but new)

The problem that I'm facing now is that I can't seem to shift into my lowest gear.

Derailleur hanger doesn't seem bent.
The derailleur itself doesn't seem broken or bent.
I also know that it shifted into the largest gear before so whatever I did must be fixable.

Here's a picture when I'm shifted in the lowest gear:
Either the L screw which limits how far the derailleur can move towards the wheel is too far in or the cable tension is too low.

Try to increase the cable tension first by turning the barrel adjuster on the derailleur counter-clockwise. However, it looks like it’s already pretty far out. If it’s at the maximum you have to shift to the smallest cog (highest gear), screw the barrel adjuster all the way in, unclamp the cable, pull on the cable as far as possible (pliers help) and then clamp it again.

If the cable tension doesn't help you have to turn the L screw counter-clockwise to allow the derailleur to move farther. Don't turn it out too far or the chain will fall over the cog into the spokes.

Park Tool offers a good tutorial here: https://www.parktool.com/blog/repair-help/rear-derailleur-adjustment