"[Fedora Media Writer] writes any ISO."
My apologies, you are of course correct. I skim read the first of the links
you shared, and got the impression that the instructions given there was the
limit of what the program could do. Now that I look again, the images make it
clear that impression was, as you say, quite incorrect:
It would be interesting to see what libraries and other dependencies FMW is
using under the hood, and how they compare to those used by Etcher. I will
suggest to The Assassin that we have at least a cursory glance at the FMW
code (as well as the UNetbootin code) as part of creating our fork of Etcher.
Perhaps forking an app other than Etcher might be easier or better, or
perhaps we can hybridize the best elements of multiple programs.