You're blowing this entirely out of proportion. The vast vast majority of apps work without issue with sandboxed play services. Yes it's less plug and play than a stock os. No it's not a life-ending inconvenience.
Use aegis https://f-droid.org/packages/com.beemdevelopment.aegis/
Thanks for the link, I'll take a look. I might just move it to a secondary device first.
My uni does it and I've had use the only alternative option, cell call, and rigged Tasker to automatically answered and play the needed tone so I don't need to carry it with me.