Hardware person here, these standards groups are getting out of control. They want thousands of dollars from anyone who wants to make anything compatible with their specs and while hardware and drivers are becoming cheaper and easier than ever to get into, they have become the main roadblock.
Isn't it possible to make something that's technically compatible with HDMI as long as you don't call it HDMI, or say it uses HDMI. I've seen different projects go that route, maybe you might be able to as well.
DP is by VESA, who brought you such bangers as VGA, DVI, standardised mounting systems, DDC (which enables EDID), EDID.
Although there is controversy about them not supplying the standards documentation for free, i dont believe it is licences
There's also the option of getting a DP to HDMI converter. I'm personally waiting for one that supports DP 2.0, along with VRR and HDR10+. There's a DP 1.4 one right now, but AFAIK it uses DSC to display the full 4k120, which isn't lossless.
Unfortunately unlikely to both. The displays all likely have the same controller boards with HDMI support baked in. The TVs are going to be made for people who still have cable and streaming boxes, and unless something has changed, those are all HDMI. Unless a manufacturer not in the forum decides to make a display, I don't really see anything without HDMI existing.