I understand the frustration. I think at one point in time, the Freedoom project was moving in the direction of cloning the Doom assets closely enough that it'

I understand the frustration. I think at one point in time, the Freedoom project was moving in the direction of cloning the Doom assets closely enough that it'd suffice as a replacement for the original iwads, and as such would've made a setup like you described possible (without committing copyright infringement). People argued that the iwads are easy enough to get now, and somewhat recently, the freedoom project seemed to take on a new direction, which is less about making close clones of the original assets and more about being a game on its own right with its own theme and roster of enemies and all that. It's a bit weird, especially considering that they're still maintaining the vanilla gameplay elements unchanged, as if it were still built for the original purpose, yet the assets won't look good with pwads. Needless to say, I'm not super happy about this new direction. There are launchers that supposedly make it easier to run pwads though. I don't have the background knowledge to recommend one though; source ports are available to me through my package manager.