I haven't used one, so I can't speak specifically to how good it is. I can say that most of the e-ink displays you will find will not have a comparable refresh rate and be absolutely useless for any form of text editing. Your only choice will be sourcing a sketchy knock-off Chinese panel or hacking together some form of overclocked solution, similar to what DASUNG appears to have done.

> I imagine “write a display driver” is a more common job description than “write a hackintosh package”?

I dunno man, you're using MacOS. None of this stuff comes with any warrants or guarantees. What works with SIP enabled today might break the system and require SIP disabled next week. I'm not making any confident assessments on what the scale of work is because you're asking a lot here. Especially if professional use is your goal. I haven't seen people running custom Mac hardware at work in half a decade at least.