

I don’t really get the “all eggs in one basket”
I think the argument is that if at some point Proton services get compromised, or if Proton somehow turn into the bad guys, then using fewer of their services will impact you less or give you more time to react. The same goes for any other vendor, of course, which is why the way you address this is by spreading your trust across different services/regions/owners/…
2FAS and Ente are two open-source alternatives on iOS.