Coming in late to the most recent sub-conversation, regarding PF2 challenge level. I think I'm figured it out (or what works for my preferences, anyway).
You can do Severe (or even Extreme) encounters, so long as it's assembled with creatures that are 1-2 levels lower than the party, with maybe a couple creatures that are of the party's level. With that assortment, you have a dynamic battle that is somewhere between the PF2 "everyone has to be on their game 100% of the time" and 5e's "you can steamroll most fights on autopilot."