If you want to sideload then buy an Android... they are even cheaper. It's not like they pulled the rug out from under you: you already knew you couldn't sideload when you bought the phone.
Situations and therefore opinions are allowed to change over time. I could argue they pulled the rug out from under me when they removed Fortnite from the store, or started blocking apps I want such as Stadia. It's not like it's advertised on the phone "Hey we'll remove any app from the store that we don't like".
This is all done using the excuse that they are curators that want to give you the best possible experience. It has worked wonders too because now we debate not with these companies and their hired help but with others who have been screwed over just like us but are thankful for the experience.
I see this highlighted all the time. When people agree with how something works then there's no comment. When it doesn't work how they want they believe they're being forced into a novel love-it-or-leave-it scenario, when the reality is they are in those scenarios all the time (daily/hourly even) and support them as well. Don't believe me? Ok I want less battery life on the iPhone and for it to be cheaper. Now what? You'll say "cost is important to you there are cheaper alternatives like X, Y, and Z". Same song.
tl;dr yea just buy an Android phone if sideloading apps is the killer feature for you. If I want the best battery life or the best camera I can base my purchase decision off of those product features. Sideloading apps is no different. That's a fact. Jack.
If side-loading is the only feature you care about, Android is for you. If it's one of many, you may have to make a trade off or pick between different mixes of features. This is just how the world works and always will work.
Not all get to have a market specifically for them.
If I'm gonna be ruled by an authoritarian mobile OS that constantly tries to "engage" me, I might as well go for a nicer one that still cares about UX and being less buggy.
iOS is straying further and further from that path with every release, though. It's not Android-level, but it's far from what it used to be.
The fastest Android SoC is as fast as the A12, a three year old chip.
Android phones are lucky to get 1 major version upgrade in it's lifetime and that's usually 6-12s months after the latest version is released.