An 'ideal' solution might require a complete redesign on how federation works.

Something like a more decentralised network where you don't have a 'home' instance.
An instance would be more like a relay into a 'core' network, and you could swap between them at any time.

It'd probably require your account info to be public though, so passwords wouldn't be possible to implement in a foolproof way.

Instead of signing in, your device could generate a public/private keypair on signup.
The whole network would have your public key, and only content/actions that your device signs would be propagated on the network.

Sorry, you probably don't care about my ideas lol. Just thinking out loud I guess.