I am trying to create a single life-management app (calendar, tasks, bills, notes, goals, reminders etc.) too.
FOSS, self-hostable, obviously. I've been developing it for 6 months as of now, and I am actively working on improving it and making it available in F-droid (and the Play Store too, for that matter)
It's meant exactly to help people deGoogle themselves.
Anyways, I don't want to be advertising it too much because I am new here and don't want to get banned, but I think this is very much justified, whoever wants to check it out, here is the GH repo