I think I didn’t get exactly what you want. Ant it keeps me wondering that perhaps there are a few concepts not so clear.

Do you want to receive streaming from a server? do you want to setup the server? Or something completely else?

If you want to receive the streaming from a server, the most compatible cost-effective solution is the Amazon fire. Works with remotes and you will be able to play every media you have because the server will transcode the file on the fly if the fire stick doesn’t support the format.

If you want something more open to tinker or to get more functionality then a raspberry pi will be enough, because once again, the heavy lifting is done by the servers (via plex server or moonlight server).

More powerful boxes exists but then you need to start thinking carefully what is your use case for not eating money.