The thing is, even though many of those products are custom designs, they still for the most part use modern (and in many cases off-the shelf) components. The real stumbling block for a boutique CRT monitor is that the assembly lines for those tubes just don't exist anymore, and standing one up is likely beyond the means of what the scope of that market could realistically support.
Well my ideal would be something the size/weight/thickness of a LED monitor with no perceptible different in input lag from a CRT, taking in feedback from speedrunners/fighting game players to make sure everything is fucking PERFECT down to the frame when it comes to replicating the CRT feel. I ain't no scientist so I don't know how possible it is, but that's how I dream it up in my head. It wouldn't be a huge, heavy fucker like any other CRT, because if I wanted that I would just go on craigs list and get one for like $10 lol
And of course it would have all the inputs necessary for retro gameplay, and maybe even some of the options we see from the Framemeister and OSSC like scanlines and all that.
here's a basic rundown of the situation as I understand it. the focus is melee but lots of info in there on CRT vs LED lag:
I'd like the CRT method of drawing images on a screen with a LED form factor