I've almost completed that quest! Here's what I'm using:

Google > Kagi

Android > Calyx

App store > Fdroid and direct download of apks (just starting to try out Obtainium)

Email and calendar > Proton

Drive and Docs > combo of Markor and Syncthing for notes, and using Yunohost to host Cryptpad

Contacts > OpenContacts

Messanger > Beeper (a new addition, still testing), was using an sms app from fdroid

Authenticator > Aegis

Keyboard > Thumb-Key

Books > Voice for audiobooks

Only thing I have left to replace is the camera app, seems like nothing comes close, though I do use a different gallery app from fdroid.