@matt There's a tool called slurp that can import your old posts from an exported archive. I used it to import my photo posts from Mastodon and Pixelfed to GoToSocial.
https://codeberg.org/vyr/slurp
It uses the Mastodon API to do the importing, so in theory it should be able to import to snac as well (which is the other good choice for single-user self-hosting, IMO), and apparently it can import Bluesky archives now too, though I haven't tested either of those.
@matt Anyway, I'll vouch for both GoToSocial and Snac for self-hosting, depending on your priorities. Snac is really minimalist in terms of resources and appearance, but unlike GTS it does have a web interface for reading and posting. GTS is a lot more polished, and has been doing a lot of work on trust-and-safety type things like subscribing to block/allowlists, setting reply permissions, and so on.
I currently use GTS for my personal accounts and Snac for a bot. I've also reviewed both of them on my website, in case you're interested in more detail: