Roll your own. I've got one running PiKVM software on a Pi Zero 2W with an AliExpress HDMI-CSI board connected, and the whole thing bundled together with kapton tape and hanging off the USB port on a headless system. I had to mask off one pin on one of the two microUSB cables. I think I'm into it for about €50 including the Pi0. The instructions are/were on their website.