So one should configure an alternative user for each group of permissions that any arbitrary app might need? Then what happens the day that I do decide that my weather app should access e.g. my location? Now I should move all its data and update my launch scripts to the new user?

I happen to dislike snaps as well. The hard coded install directory is a passion point for me. But at least the permissions issue they are getting right.

I wish that desktop distros would adopt the Android permissions paradigm.

No, you can create groups for permissions that you'd like to enable and disable and add the user to the appropriate groups.