Yes, alternatives exist. But they can be... how would one put it? Relatively rare and expensive.

I am aware of single board industrial replacement alternatives, but those can be hard to get a hold of, depending on location. Shopping around for used, older thin clients that still have the right I/O and compatible-enough hardware is honestly not a terrible idea, although weirdly the video that you sent as an example highlights a bunch of caveats and issues I wouldn't even have thought about. Still, that one may be a fun project, if slightly not in the spirit, certainly off-spec for the period and definitely not plug-and-play.

Ultimately, though, I do see the appeal of a period-approrpiate, native revival device. Clearly not alone there, hence the OP and the viral success of the Hand, with all its limitations. I'm not saying you can't work around the need for that exact thing. You can and I have. To repeat what my first response to the guy was:

"It's not like there aren't ways to get there now, they're just... relatively rare and quite expensive."