I have some maybe recommendations. Take these with a grain of salt as I've not tried them for this purpose.
Savage Worlds supposedly players a great zombie game.
I do have a lot of digital SW stuff, I'll comb through it again.
I hear good things about the Alien TTRPG.
It's a good system ( I LUV the stress system), but not really for what I'm aiming for.
For board games. I hear mixed things about Zombicide. Good prodiction. CMON (the company that make it) hit some financial troubles recently.
Already covered there. Got 2.0, Black Plague, Night of the Living Dead version, the military base campaign, urban legends, even the Monty Python supplement. It's a decent enough pick up and play and the figures are good molds. Again, not quite the jib I'm hunting for.
For a skirmish system. The one page rules RPG mode (heroes vs hoards) might work.
I have the OPR Grimdark Future stuff, is that a different product?
You could also try One Hour Skirmish Wargames. Ranged combat is safe, but guys keep getting up, and melee combat is decisive and deadly. One Hour Fantasy Skirmish Wargames is more melee focused, but I don't know how that works.
Funny story about OHS. I actually picked up Red Ops 5 and another supplement, Asylum, but realized that the latter had no rules for what I was really hunting for, namely a creation and campaighn system, it just had the OHS core. I communicated with the OHS people and got told the older books weren't going to be compatable with what they got in the works, linked me to the new core rules instead. They're a current candidate, but what the hell, OHS?!
Two more war games. 5 Parsecs, or Stargrave with the zombie expansion.
I poked around 5 Parsecs and 5 Klicks from the Zone. Stargrave has a zombie expansion?!
I have played the RE2 board game on TTS, but don't remember much about it.
Again, I have the RE1 board game already so figs and some indoor mansion tiles are no issue.
Finally, might be worth looking into the Aliens board game, Core Space, or Maladum. These might have the same issue of long set up time, but also have fun minis.
I have Another Day in the Corps, can't see adapting it given the heavy reliance on card mechanics.
Got Core Space (if only for it also including Battle System terrain), it's a candidate. Regular Purge robots can easily be adapted to zeds. Not sure about the rest though.
Can't comment on Maladum. No idea, but will look.