My method for android & desktop. I never sign in to YouTube & never use the app. Using Joplin synced through Nextcloud (any syncable note taking app would do the trick) I keep a list of channels (“subscriptions”) & interesting looking videos (“watch later”) which I group by length. Obviously, this way the links can be via Piped, YouTube whatever.
As a Joplin user, I find it interesting. So you have a "subscriptions" folder and a "watch later" folder? What is your routine?
Thank you for describing your system. I didn't even know that table of contents were available in Joplin.