I had been asking all these questions too as I had been an avid linux-ue user from few years.
think it is easier to get response from ::: u:s.g.o.v ::: than from epic 
(using ‘change.org petitions’)
can we linux developers file a petition there for this!
Also maybe another petition to nvidia to give nvapi/rasterizer for vulkan/linux (for nanite)
Joke aside, if you look through my previous post you will get answers for some of those questions.