Recommendations for a KVM (peripheral sharing) w/o VGA

So my old work/gaming PC is slowly becoming my work-only PC and has to stay as such. Therefore I'm building a small mATX gaming machine for extracurricular activities which will sit desktop-side whilst the old PC sits under the desk.

Initially I was thinking of just getting another gaming mouse and a wireless keyboard which would be stowed away until needed but audio was going to be the main conundrum plus its extra stuff to store somewhere. I did a quick search and came across I device I never knew or had reason to know about before - a KVM. I imagine many of you are far more familiar with them than I am but as far as I understand their main function is to provide varying forms of peripheral sharing for 2 or more computers. Most of them seem to allow sharing of VGA (seems outdated? some appear to have DVI) mouse/keyboard (via ps2 or usb) and more often than not, audio.

As far as video sharing goes I have a monitor with a decent amount of connectivity (DVI/VGA/HDMI/Display Port...) so I thought that sharing this was not going to be a problem. I currently use the DVI but I assume I can stick the new PC into a HDMI or Display Port and use the monitors OSD to switch between the two - I've never used the monitors other ports let alone had more than one device connected at any one time so I hope I'm correct in assuming that will work?

If that is the case it sort of makes the video sharing aspect of the KVM irrelevant, therefore, is there such thing as a KVM that only shares mouse/keyboard [usb] and audio. If I don't need the VGA it would be more efficient/cheaper this way if possible. Any information or recommendations from those more informed would be much appreciated.

Monitor input switching should work fine. I have switched eg workstation to server like that, though they did have their own keyboards.

Not heard of a keyboard switcher, but the hard part of a KVM is switching the video so if you aren't doing that then any cheap kvm should work.

Here are a couple of other non KVM suggestions that you might want to play with though. I have used all these successfully in the past.

I will assume here that the new PC will be faster (simply as it is newer and will probably require better graphics).

1/ Set up the play PC as main PC, networked to Work PC. Remote desktop into the work PC when you want to work.

2/ Ditch the work PC, and create a virtual PC on the game PC. When you want to work, fire up the virtual PC.

3/ Have a hard drive for work, and a hard drive for games. Keeps the two seperate, dual boot between them. My home PC is like this.