No, written from scratch in manifest v3 with minimal permissions

Libredirect is a manifest v2 extension (can't be published on chrome store) and has permissions for all_urls, predirect is a manifest v3 extension and only has permissions for necessary domains

The extension currently doesn't handle YouTube.de (unless it is redirected to YouTube.com) but you can choose your custom instance. I'll add more features soon

Yes, Predirect currently chooses randomly from list of instances from farside/official(I'll make it updatable/refreshable in near future) or one custom instance (I'll also add editing list of custom instances in far future) [ofc if chrome store allows these two]. I didn't add libredirect/reddit due to ratelimiting problems and GotHub, anonymous overflow due to usability issues. I'll add search, maps in near future and also others. Predirect does distribute traffic by randomising instances so not an issue. Thanks for suggestions and contributions are welcome for any of these

No, both manifest v2 and v3, but in earlier versions add-ons had to be vetted by reviewers or manually added to their account collections by users, but from v121,all extensions marked by their devs as compatible are available to everyone https://blog.mozilla.org/addons/2023/11/28/open-extensions-on-firefox-for-android-debut-december-14-but-you-can-get-a-sneak-peek-today/

There is an onboarding step for permissions in firefox version(due to more restrictions in manifest v3 than even chrome),so you need to grant permissions, unstyled UI is intended but I will add style with a minimal ui css framework in near future

This permission doesn't mean I can access your data for every site, this is an advantage of manifest v3

Firefox is stricter than chrome in manifest v3 that it provides no way to request host permissions at install time, there is a onboarding page after installation of addon where you can grant permissions to hosts

Yeah I will add refreshable list of instances, custom lists probably not(extension stores has many restrictions on remote code loading)