JoshStrobl Thank you for your answer!
I like that Lutris is a library of games - for convenience. Though I must say I didn't realise Solus had GZDoom in the repos!
If my logic is right, installing GZDoom from the repositories should give me all the dependencies for the runner on Lutris, right? I could then, in theory, remove the GZDoom install that came from the repo to avoid duplicate installs (I think?)