For those that don't know, GrayJay allows consuming media from many platforms, all in one app. Peertube, Odysee (lbry), twitch, kick, removedute, nebula, soundcloud, and more!
You can also sync your playlists, watch list, subscriptions, and so on across devices.
I've discovered interesting creators across multiple platforms (peertube, odysee, billibi, dailymotion, ...) and have reached the point now where I can just switch of the youtube source and just consume media from all other sources. Billibi (Chinese youtube) for example has accounts that just sync/copy/rip entire channels from youtube and there are some creators that sync their channels onto peertube, odysee, or elsewhere. With Grayjay, it doesn't matter where anymore since it can probably access it.
What I enjoy a lot is not worrying about youtube updating and breaking the plugin because I just don't consume it anymore. You can give it a shot too.
If you search for the youtube title and have the youtube source/plugin enabled, if the video has been mirrored to another platform, that will come up. If not, then you can choose to enable the youtube source/plugin. Search results don't seem to give priority to any platform so order can be random.
You can find the source if you search for it. There is a guide for how to write plugins. If you understand that, I guess it'll answer your question. You could also ask the devs. They probably have a good answer.