At least for QEMU (tested 6 months ago) I know it doesn't need those non-free software (be it BIOS or not).
For the rest, it's been 3 years since I last checked, but I remember that most of those provide a default "simulation of a BIOS". But not the actual non-free BIOS. Free/libre software can be developed or used to be run once this "simulation of a BIOS" recognizes those as runnable. Interestingly, I remember some years ago that the following games work by default: - Escape From Pong (can be found in Trisquel's default repositories). - Flight of the Amazon Queen (id.). - Beneath a Steel Sky (id.). - Drascula: The Vampire Strikes Back (id.). - Lure of the Temptress (id.).
