Ok, so I don't agree with the OP on everything said.
That does not mean that I do not find the post well written, and actually funny- even hilarious- in a George Carlin sort of way.
I might even agree with a lot more of what was said if I was still trapped with my first Android device.
I had all the same issues as OP, at least when I first started and had no clue as to how to fix them.
Even now, I still have the issue of some caches filling up with useless junk and dropping anchor on the performance of the app and the device.
Sure, tell me about how I need a device with more memory, and then I won't have that issue.
The point remains that the caches of many apps will fill up with 1GB (or more) of crap that will never make the apps or device work better or faster. More memory on the device is not a viable solution. When I make more room, the caches grow even larger.
The simple solution is to contact the developer(s), and see if anything can be done. If not, then ditch such apps- because the programming is bad, and there are sure to be apps out there that perform the same function but do not store hoards of junk for no reason.
As for the data mining, this is also a reality.
Once again, the solution is to find and then use privacy oriented apps that do not do such things.
Stay (far) away from Google Play Store. Often, even apps available elsewhere have Google trackers on the version available there.
Use FOSS apps as much as possible.
Use a VPN (Proton VPN).
Use a firewall (NetGuard), to control what apps even have access to the internet.
There are even apps that allow the user to control exactly what internet connections can be made with each app (Tracker Control).
If I can have and use these on the cheap, low powered devices that I use, I can't think of a reason for others to not be able to as well.