You can easily deploy Invidious on that Mac as well. Just use Docker, Invidious has pretty good documentation for that: https://docs.invidious.io/installation/#docker-compose-method-production
I used to host Invidious like that on a Mac for almost a year, it worked flawlessly
If you host your own private instance, it’s less likely to get blocked. But quite a few public instance are having trouble right now.
Grayjay is source-available, but not free & open-source software.
Downloading YouTube videos works, but it’s probably not the desired workflow for most people. It takes up storage space on your disk, and you have to wait for the video to download, before you can watch it. I like Tube Archivist, and use it myself for archiving videos, but I wouldn’t consider it a great solution for just watching videos. I think LibreTube, FreeTube or a self-hosted Invidious instance are better solutions here.