@apokrif @maco I don't think that data contains people's bios, pinned tweets, etc. so you'd only find people who have the Mastodon link in their display name, which not many due (and it's discouraged because it messes with screenreaders). (Actually I'm not even sure if the display name is in there; it's been a few months since I looked at the format.)
The server would have to pull that data from Twitter, and then you are back at the exact same API rate limiting problem as before.
Actually, Debirdify did have functionality to process Twitter archives like that, but there wasn't much use for it.