This one actually works! Many thanks.

It's good because it lets you define the instance URL in the add-on preferences. But it doesn't support YouTube channel links, and search pages.

Best I try... because I can configure my host_server name easly

Now that @doronbehar dropped his extension I found this jewel that actually allows you to go back to youtube if you need to for X or Y.

It's nearly perfect. Only caveat is that you cant go back to your invidious instance if you went from it to youtube.

Say you do this:

Open a video on invidious > click "Watch on YT" cuz you want 4k > you are done watching the video but you found a cool recomendation, you click on it > it loads on YT

At this point it would be neat to have a button that takes you back to invidious.