Pretty much anything – I just bought a random cheap one from Amazon, though you might get better latency for more money. The dongles show up as USB cameras (ie UVC) which is supported since iPadOS 17.

I use the (free) Orion app, but it's basically just a fullscreen camera preview so there are plenty of other options.

Seems interesting. To bad you cant buy it yet.

Yes, although NanoKVM is probably a product with most caveats out of competing ones to recommend. https://www.youtube.com/watch?v=plJGZQ35Q6I. I'd recommend JetKVM instead, but unfortunately it is still only available to obtain through late pledges on Kickstarter.

Nice. Was going to mention TinyPilot but this seems even more portable.

Do you often connect a monitor with keyboard via serial? Obviously I meant seeing boot errors of some linux machine, which is what usually monitor is for, but you have to be there, on site, with the monitor and keyboard to hook it up and see what the problem is. This is sometimes not possible and NanoKVM or JetKVM would be very helpful. I do not see relevance of you comment here. I hope you at least had a nice time writing it because it was otherwise a waste of time.