The MS Office for your personal life

I think the important thing is the diary.

A frictionless diary app, plus something equivalent to Google Keep, Contacts ,and Calendar, would cover most of my personal use cases other than ones that need hardware(I think having NFC or Bluetooth cards to put digital notes in physical space and be able to hand them to people would be a big thing).

Google already has a great suite, just missing journalling, and it's not FOSS or as tightly integrated as it could be..

Hashtag autocomplete across solve a lot of use cases that normally need a database. Who needs a customer relationship manager when you can just add @Susan to your diary entry and calendar stuff and have it all link together on the contacts page?

Another important one is scanning. Having AI scanning to make nice PDFs from paper documents would be great, for a true "All your personal data in one place" solution.

Some kind of RSS like mechanism to subscribe to bank statements and the like a d import them to your digital storage space would be amazing.

A personal inventory management app would be super cool. Although I don't really see how it would be possible without cheap EPC scanning or similar, the overhead of manually tracking things seems like too much for most personal use cases.

SyncThing already provides a perfect backend, so it should all be possible without any cloud work at all.