Mobile developer here. Somewhat. I've written mobile apps for my internship and I have some several hundred hours of experience.

This is because Apple provides a much better SDK and, most importantly, the fact that all the iOS devices actually get updated means you are not stuck needing to support ancient SDK versions and you can freely rely on newer methods more easily

Though my personal phone is Android. I see the difference in polish between most iOS and most Android apps, but I think that's an objective difference but a subjective trait. For now I still prefer Android: while everything is still a little more rough around the edges the gap has been slowly closing for s few years now, Material You is finally really good, and gone are the days of the fiddly Android phones that never worked quite right or needed the occasional trip to recovery mode to wipe /cache to stay fast or the occasional factory reset: modern Android is much different, it's basically fully immutable in a way where every action is completely reversible, and it does a much better job at maintaining itself than it used to in the past.

Still yes, for people who value the slightly higher polish on native iOS apps, being able to sideload as well is big. It would make me at least consider the iPhone. A lot of the apps I use every day come from F-Droid, and F-Droid is where I look for my apps first when I need something to fulfill a certain purpose. I'm pretty big on FOSS, but I've never been able to truly commit on my phone yet as it's not really ready for my use case yet (mostly, weird bugs and missing features in MicroG). So it's not FOSS Vs Apple - it's Google vs Apple in my case, so neither is an ethical choice.