i made a CLI tool for moving data in and out of GtS and Mastodon instances using the API: github.com/VyrCossont/slurp
it can handle CSV data in Mastodon export format for blocks, bookmarks, follows, and lists. there is no Mastodon CSV format for filters so i made one up. (note that you need to be running GtS 0.15 for filter support.)
it doesn't handle posts or media yet; i have ideas about extending the GtS API to allow backdating posts and suppressing push federation, but probably won't get to that for a while.
GitHub - VyrCossont/slurp: tool for exporting data from and importing data to Fediverse instances
tool for exporting data from and importing data to Fediverse instances - VyrCossont/slurpGitHub