The standalone list doesn’t mention it, but Neko can import the Tachiyomi backup, though only the Mangadex manga of course. It’s also actually a Tachiyomi fork and was endorsed by them until Kakao struck AFAIK. Figured it was good to mention.
Do you need to reinstall the extensions for this? I can’t get it to work with TachiyomiSY. Edit: maybe some extra context: TachiyomiSY is still attempting to fetch stuff from the removed repo, even though I’ve added the new one, so it still fails.