This will help bring back most/all of the extensions. As for untrusted sites, just click it. Although, I am not sure if updates for that extension are still going to work.
Probably not, they explained it in the FAQ, it's different storage formats and Tachiyomi has their own file extensions wich they can't work with... MANUAL MIGRATION IT SEEMS...
i need a week for that... 2k Mangas to migrate :/
It would be cool if the anilist sync would be bidirectional this would solve the problem.
No, you can't. This is due to the difficulty in supporting and adapting the .proto.gz or .tachibk format that Tachiyomi uses. Also Kotatsu and Tachiyomi and its forks have different data structures that they use. For Neko for MangaDex users we recommend to use Nekotatsu.
I wonder how reliable this workaround will be in the future. Will the external repositories be purged in the future as well? Perhaps straying away from github is a more sustainable answer.