Typically, you can find the setting by holding down on the app’s icon, tapping the icon that looks like an “i” inside an “o”, and tapping on “Open by default”. After that, make sure “Open supported links” is on, and then tap “+ Add link” to add more supported links. That’s how it is on my phone, anyway.
Like you said, if you (or Google) have already set a default (for example, YouTube links always opening in the YouTube app), you have to go in to your YouTube app settings (same way as described above) and switch off “Open supported links”. Then you can go into the other app’s settings (Newpipe, ReVanced, etc.) and make it the default.
Typically, you can find the setting by holding down on the app’s icon, tapping the icon that looks like an “i” inside an “o”, and tapping on “Open by default”. After that, make sure “Open supported links” is on, and then tap “+ Add link” to add more supported links. That’s how it is on my phone, anyway.
Like you said, if you (or Google) have already set a default (for example, YouTube links always opening in the YouTube app), you have to go in to your YouTube app settings (same way as described above) and switch off “Open supported links”. Then you can go into the other app’s settings (Newpipe, ReVanced, etc.) and make it the default.