I like ksysguard, comes with basic system monitoring screens and is very configurable.

Yessssssss I’ve been waiting for so long for this

There are quite a few options.

A popular one is https://phtn.app/

This thread has some more suggestions.

If you’re willing to replace your Chromecast, you could configure your raspberry pi (or whatever Linux based replacement) to use a remote Pulseaudio server.

KDE Connect has media controls, among other things. It’s great as a remote control for your PC, I’ve used it countless times to control media playback, presentations, …

Instructions per cycle

Was what I first read anyways