I’ve been toying with an alternative, SportsTrackLive, for quite some time now. In my opinion, it’s actually a much better product than Ayvri, but the big downside of it is that you have to have a paid account even to watch (otherwise, you get nagged every 2 minutes while watching). It doesn’t prevent you from watching, but just kind of an annoyance. Perhaps this will change in the future.
The developer is very responsive via their Discord – maybe if enough of us start using it and provide that feedback that this will change in the future. Personally, I’d be happy to pay a bit more for a subscription if that nag would go away for others watching.
Edit: the “nag” time limit looks like it’s been increased since I last used it (watched one of my longer flights and never saw it pop up). Looking like a better option.