I can’t find any “funtax” user in the linked openairplay repo, but it appears that I have completely missed pyatv’s ability to stream video. As long as it can stream video I think I can make it do screen mirroring too. Thank you very much, I will be looking into pyatv now!
Your link doesn’t work, but I still found what you mean. I think at that point I’d probably look into the Microsoft Wireless Display Adapter or something similar instead, as Miracast on Linux actually works quite well with GNOME Network Displays. But my current goal is not having to connect any additional hardware to the projector, so I will be looking into pyatv for now.