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.