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

Yessssssss I’ve been waiting for so long for this

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, …

I’ve changed my OS three times since I set up my main games SSD (where my steam library lives) and with each OS change, I copied my .steam folder from home to the new home folder. Had zero issues with family sharing.