Does this only work for Windows?

I was hoping for something cross platform. Since synergy sucks and will probably continue to suck for a while, I'd like to find something in the interim, or to replace it entirely so I can control a Linux system from my windows PC, or something like that.

Don't get me wrong, this is great for Windows, but I originally got synergy because I was using a Linux system as a media player, so I could mouse over and change tracks or load a playlist or whatever I wanted to do without having to reach across the room for another keyboard or something like that.

I haven't used that set up in a while, though I might switch back to it with a raspberry Pi or something eventually, and just have a small micro system playing media using chromium to load up YouTube music (or whatever). The old set up was the Linux system using xmmp (I believe) to play music from a NAS. The output went through a physical mixer, so I had immediate access to turn up, or down, the music from my media system, without dedicating resources to music on my main (gaming) system. This was back in the days of Windows XP and I wanted to squeeze every last FPS I could from my main system, so I offloaded my music to another system; which was some old P4 that I had lying around. The HDD was questionable so I never put anything on it that I couldn't lose, hence all the music was on my network storage.

At the same time I was using the network storage system (I call it a NAS, but it was really a Windows box with some file shares) to do other offloading tasks, like downloading Linux ISOs from torrent files.

I did a lot to ensure my system would not get bogged down. I have servers now for any file shares and torrent stuff, but I've never solved the media system problem. Using a pi or similar SBC and piping the audio through the mixer I still have connected to my main computer is still appealing to me.... Among other things... And just putting up a display for it next to my monitors and roaming my mouse and keyboard to it to pick what I want to watch/listen to, still seems like a good idea to me.

I don't want to get restricted to Windows to do it though, since then I would need a much more power-hungry system to run it. I've concerned myself a lot more with efficiency since I was younger, considering that I'm paying for my own power now. Historically, I would be paying for it through rent that includes utilities. I own a house now and pay all my own utilities. So a sub 10W pi sounds good. Most windows systems, even very lightweight systems usually need at least double that.