Technically you would link your instance to content in your #Solid pod to create a post/toot. And when you migrate between instances, you "simply" replace the links. The instance could cache the content to speed up delivery and federation. But you would be in control and can also see how your content spreads without having to rely on third parties. Think about it :) More decentralisation. Better business opportunities.

What we really need in the #SocialWeb, as the next iterative progression of #ActivityPub and its implementations like #Mastodon etc. IMHO. https://solidproject.org to store all posts and pictures etc *per user*, not per instance or account. This would radically reduce the scope of an implementation and allow for frictionless migration between instances. This does NOT necessarily need any change to the standard. It's an implementation detail, AFAICS. #SocialCG