Yeah Mongul would be...
difficult to pull off well in any kind of long-term capacity (that is, more than an episode) on a TV budget, I'd imagine. In my hypothetical dream Supes show, I did have a multi-episode arc that was basically a space adventure - "The Trial of Superman" storyline from the 90's combined with the Mongul/Warworld portion of "Exile" - but that dream show would have a proper HBO/blockbuster budget.
On
this show, I'd imagine Supes will have had his Warworld adventure in the past, so if Mongul shows up here, it would be for a relatively brief appearance in an attempt at revenge. If they don't want to do a new take on the classic Black Mercy story, they could borrow from Mongul's GL Corps history, where he got a hold of a Yellow Ring and used it on the Black Mercy planet to modify the Mercy plants to trap people in their greatest fears instead of their greatest desires and then sent the seeds out to planets all over the galaxy. Or maybe he wants to force Superman to help him get Warworld back from Brainiac. I think that was a thing once, too.
I dunno, I think if they're gonna do an intergalactic conqueror pulling the strings BTS for a season long arc, Darkseid makes a little more sense than Mongul. He's got more minions, more omens/harbingers, and manipulative powers to work with to build an arc like that. Or, of course, Brainiac, who has all sorts of methods for a "stealth invasion" before the main event.
