Louis Rossmann unveils Grayjay - a video client similar to Revanced and NewPipe, but shows your subscriptions from various video sites in a single feed.
Site: https://grayjay.app/
Source: https://gitlab.futo.org/videostreaming/grayjay
The app is OSS but not Free, which I’m personally completely OK with.
Watch elsewhere: Invidious / piped link in comments
Have you watched the video? It uses video platforms for what they’re good at: storing videos, Without limiting to only one platform and having an open source comment and subscription system on top.
YouTube can’t block this, they would have to get rid of their website and only rely on its own app to really block access.
so, they have already blocked third party apps, notably when Microsoft and when Amazon made apps, both got blocked. So no not really, they can block whoever they want.