Aaaaand now I'm carrying around a laptop again, at least mini pcs are tiny now, maybe a small handheld would do...

if any of this shit hinders me, I'll get a dumb phone and the cheapest iphone available for manditory work-based things and say so-long to being a mobile OS user.

That doesnt appear to be true, the restriction seems to be on apps being installed from file managers, web browsers, messaging, etc.

F-droid and the like are not part of that list.

This still isn't good, but it doesnt stop you from having F-droid manage your messaging apps it would seem.

Edit: If you're down voting because you think its using the same method as a file manager as the user that replied to me, this is incorrect. This is also an issue going back several versions.

F-Droid uses a session installer method for 3rd party app stores, it does not use the same method as a file manager.

For an article about a similar issue brought up by similar restrictions in previous updates, you can refer to this article:

https://www.androidauthority.com/android-15-restricted-settings-sideloading-3481098/

You can also refer to this thread in the F-Droid forums which covers this as well, from 2 1/2 years ago:

https://forum.f-droid.org/t/sideloading-restrictions-or-removal-in-future-how-it-effects-fdroid/21089/10

Which also includes a merged discussion from the last time this came up 9 months ago.

F-Droid has been using the session installer method for quite some time.