As someone who has done this, including project fi, I maintain my own backups on a personal server at home and another one on a VPS.

Owncloud / nextcloud provide automatic syncing of photos if need be. I sync up all my important documents but as of now I don't see the point of backing up my emails. The last missing piece is syncing my contacts which is also possible in my current setup.

With that said, I am still going to use Google services because of their convenience. I just like knowing that the data I care about is safe.