I think the benefit for you, without knowing what you self-host is, that you could use apps using your data storage, instead of proprietary e.g.: Email. Of course this needs the presence of data layer, plus new apps.
The running server locally, I meant like citrine. It would run on your phone, and you could share files with someone else on the go. But can also be an easy PC app. The idea behind this would be a way to support something similar like apple handsoff.
I was also thinking about the whatif of key compromise. I guess, you have the same with using a google account. But at least there "they can save you", but also "lock you". On the other hand, you can change passwords.
I would definitely not use the same keys.
Lets make a thought experiment.
Whatif
- you have "master key", "recovery key, "account keys" and "action keys"
- "master key" is your login, and it is not connected to any account.
- "recovery key", is to reset your account if you lose the "master key"
- account keys are the keys you post on behalf of
- "action keys", delegated keys to use inside apps (what nsecbunker and remote signers already do)
- you can make as much account and action keys as you want
- you can set max priviliges/allowed set of actions for all action keys, meaning all child keys can have a separate purpose. If they are lost, the damage is minimised.