I have no problem with Apple not allowing side loading. I had Android to start and got tired of no updates and higher $$ phones becoming junk after 2 years, so I switched to Apple years ago. Started with a 5S used for $100 ( it now sits in my FLIR enclosure for IR heat reading when I added insulation to the attic ) and then got a 6S ( used for $130 ) which is still in use as a personal phone and a then a Refurbed from Apple 8,  2 years ago for 379, for my business. My only gripe with Apple is not allowing developers to access the WIFI so I can see what Channels are being used when I do Network/Internet work at customer's place. ( I do IT work and have for decades ) I have an Android I bought just for that need. Runs OS 8 I think. It has AC wifi ( as well as B,G, and N ) for determining which channels are open for best reception. It was $209 New from Amazon. ( Stylo 4 )  There are other options if you don't like the  "walled garden" approach.