I’m not that concerned. There is also microg

“To be clear, developers will have the same freedom to distribute their apps directly to users through sideloading or to use any app store they prefer.”

Decoupling doesn’t always work in favor of the people. Self-hosting can do good things but again needs to be careful navigating the regulatory regime.

If you were not concerned about executing subpoenas yourself, self host, even on an openwrt.

If you have email, the Calendar, Contacts, notes/tasks, functionality can be also replicated on a shoestring budget. You might have to write some code, but you would be ok.