It's a computer, whatever headset you want to use will likely work. You'll have to pair it if it's Bluetooth, but after you do it should automatically connect. There's a Bluetooth menu on the quick settings menu.

You can start voice calls in steam as well, it's got a full set of social systems. A lot of PC players prefer discord calls though, you'd have to set that up in desktop mode and add it to your steam library so you can launch it from steam big picture mode, the default mode in steamos (at least in my experience on steam deck).

I haven't tried fluxer but it'd be the same idea. On a controller, doing voice chat over steam is probably easier.