So I downloaded the Playstation App on my Laptop and opened it in the location I plan to mostly use the device from, potentially.
I'm trying it out with Horizon - while it's not a first person shooter or something else that would require the fastest response, it's still an action game and should give a good idea of whether or not this is a viable setup.
I've messed around for about 15 minutes and it seems very promising, honestly. There is a little bit of lag, but nothing crazy. I mostly notice/am bothered when trying to make a quick, precision shot with the bow and I can observe the slight delay on the reticle. Otherwise during exploration/melee it's not all that noticeable. I'm going to give it some more time to see how it ends up feeling long term and might try a couple other genres or games to get a better idea, like Resident Evil 4 or whatever. Occasionally there are graphical hiccups where the whole screen jolts a bit with discoloration, but it seems to be pretty random, very transient, and not a bother.
So this is the kind of performance I could expect from the Portal then? It may even be able to improve a bit, because my Ps5 isn't even hard wired to the router and I'm sure that could help just a tad. The reduction in visual fidelity would also be less observable on the smaller screen.