I kept an eye on https://www.reddit.com/r/trackersignups/ (well the previous one calles r/opensignups, they open registratations every 2-4months for a couple of days usually.
I never tried donating, and it is a private tracker most foremost, torrenting replays and the likes. Live TV is just an addition, so I'd be a little weary of donating for something that isn't the main objective of said site.
you could also try your luck asking in that weekly reddit thread for an invite, it might work out
They have open signups every now and then, keep an eye out for them. It prob gets posted here: https://www.reddit.com/r/trackersignups/
I used to use https://v2.sportsurge.net/home2/ , you can usually find a working stream.
Nowadays i use https://sportscult.org, it's a private tracker that also offers live tv, and i haven't really done anything but watch f1 on there. Less ads/buffering. They have open signups every now and then.