I was wondering if and how they were using DOTS with HDRP since (from brief pokes, I of course can't speak for all of DOTS) to my knowledge, there was no major work done integrating HDRP/URP. Both were moving targets that were probably moving even faster than DOTS.

I guess the answer is an unfortunate "we did not" as of now. Real shame because the ideas of a proper DOTS renderer (not a literal renderer, moreso an ECS oriented way to deliver data to the GPU. Likely HDRP/URP) was one rumbling for years. And probably still is. And with all the industry layoffs/leavings I hope they don't drain too much of the brain to get that off the ground.