Client-side Multihoming

[SoniEx2]

Is your feature request related to a problem? Please describe. Not being able to interact with friends due to defederation sucks.

Describe the solution you'd like A way to group multiple accounts (across different instances) under the same client identity would be awesome:

• Clicking a post should fetch it through all accounts, so the replies can be combined (this allows filling in gaps where replies didn't federate to some accounts).
• The home feed should be a merged view of all the accounts' home feeds.
• The local feed should be per-account.
• The community feed should be a merged view of all the accounts' local feeds.
• The federated feed should be a merged view of all the accounts' federated feeds.

Follow requests should still be sent through individual accounts tho. Likewise, replying should require selecting an account to reply from.

Describe alternatives you've considered N/A

Additional context N/A