One thing I would like is a small portable hdmi display to use with my headless servers when they fail to boot. Even better would show screen over network.

AliExpress has a beautiful 7" screen for peanuts. It has a surprisingly clear display and has so many uses:

https://youtu.be/LC3INaZVqFA?si=2BV5N3_7TtWPRlUj

It even has USB power and speakers.

Try "camera field monitor." Example: https://www.amazon.com/FEELWORLD-Monitor-1280x720-Peaking-In...

I used one of these to make a teleprompter-style videoconference setup at home during the pandemic, so I could make eye contact with other meeting participants.

I scavenged an LCD screen from an old laptop and put it in a cheap case from AliExpress. It has a small driver board and a steel case. I use it as a small/portable TV. But it has USB-C for input and power, and HDMI input. It’s just about the size of an iPad and very nice.

I think that would work very well in a headless/data center scenario.

Peakdo have a miniHDMI 7"

https://www.peakdo.com/PeakDo-Ultra-thin-light-7-inch-Multip...

I have a portable monitor I used to use as a second screen while travelling.

I actually used it again recently while setting up a new home server, got me as far as SSH access.

It wasn't super cheap, but not that expensive either.

At a hacker conference in the early 2000s, I saw a maybe 5" cash register CRT screen on a tower server case. That was cool.

It inspired me much later to buy a 7" LCD for the same purpose. You can find them as Raspberry Pi accessories. Some of them have HDMI input, most use USB for power, and they are cheap - about 50€. The downside is that they tend to be almost bare circuit boards with a bit of plexiglass framing + stand.

There are also "DVD watching screens" for car headrests, which are more sturdy with a thick case. The downside there is that power supply (12, 1A or so) is more of a hassle, and good luck finding one without overscan. It's not in the specs if they have it or if it can be disabled.

Another option are HDMI/USB capture dongles and VLC. They’re cheap and take up no space when not in use.

How small are we talking? There are tons of cheap portable monitors built around laptop panels.