Honestly I had problems with every Miracast device I ever used. Beamers and TVs always broke connections randomly. Most of the time pairing didn't even work and failed without an error.
Buy a small PC, get one of those keyboard and trackpad things that is the form factor of a TV remote. It's more expensive but nobody can deprecate it from you and you can stream anything you could stream to a web browser or torrent onto a hard drive. I did it earlier this year and regret not doing it sooner.
ebay a few now before the prices go up and put them in a closet.
I am actively using 11 Chromecast Audios (long since EOL) in my house to send music to multi channel amps feeding speakers in my house. I ordered 5 of them within the last 6mo from Japan (ebay) at an inflated cost, but they are still available.
I still have my Chromecast. I love it. It's so easy to use and fast. I really only watch streaming and don't want to spend a lot of money on a new smart TV when my old TV still works. I have a small fire TV and it sucks, Amazon makes them cheap and it often crashes trying to load streaming services, never had an issue with the $30 Chromecast.
Did Google ever write that they are actually discontinuing the older Chromecasts? I only see that they released a new device that does not have the name Chromecast.