Is that the snap version? Or Flatpak? Depends on with one it is there is a lot of way to limit the access to maybe only the download folder.

I think he mean bottle(flatpak) when he talk about sandbox

Ublock should have the delete thing(forget what it call). I usually use that.

That is a fair point. Source first software isn’t a part of FLOSS, but even in worst case scenarios it still can be considered as “source available”. Which is better in term of transparency compared to closed source App. OP asked for “private” way to watch Youtube not open source way, so I think grayjay could still be a great choice. We are talking about watching from YouTube which is a corpo closed source spyware anyway.

Grayjay seems to be really stable compared to newpipe. I used it for 6 months now never break once. They also recently released a beta version for desktop which is quite promising

I personally think Freetube is the best for desktop right now. Recently, there is also grayjay for desktop. The UI is still buggy IMO, but also seem promising.