Played with some settings in Hard Bullet.
Only 10 enemies spawn in, but I die with a single hit.
I also just used old school guns like revolvers and shotguns.
After many failed attempts (as shown at the end of the video)
I decided I needed a planen. I spawned in a bunch of revolvers and shotguns. And placed them behind some concrete slabs. So if I get overrun and out of ammo I can just grab a new weapon.

Even with this, I died several times, sometimes VR jank, sometimes simply missed a shot I just couldn't miss.
But I did make it in the end.