There are actual wireless HDMI transmitters and receivers.

Why not just get like an onn. box and install Projectivy launcher and apps like smart tube so you don't have to use some other device to cast to it

I just hook a laptop to my TV. It's amazingly versatile of you can use a app to control it remotely. An old laptops lets you watch anything.

I have a Synology NAS that came out of the box with programs and apps that can cast music and video, including to Sonos speakers which was important to me because I bought them before they decided to make their app literally unusable and brick everyone's speakers.

Before I had the NAS I used the BubbleUPnP app to cast to my Sonos and a Google mini I have in my shower.

For tv I use an NVIDIA shield with Plex/jellyfin and store tv on my PC. The NAS didn't have the processing power to play 4k tv.

I tried multiple Chromecasts and they all crashed after a few months, before I discovered the shield. The shield has been very reliable since, highly recommend it.