>given that they made their phone platform specifically to not let you install your own operating system.

???

You can still install alternate OSes (eg. grapheneos) on their latest phones.

>And now, they're making it illegal to install custom apps too: https://keepandroidopen.org/

Besides the questionable use of "illegal" (what are they going to do, send you to jail?), that's not even accurate. You can still install apps after a 24 hour wait, or no wait at all if you use adb.