Thanks for the advice!
Unfortunately, while switching to the LTS kernel branch resulted in me seeing a different set of audio devices as available, none of them worked. This included the headphone output: none of them produced any sound through it either.
I tried searching a couple of the lines of that output with only the first seeming to really point me to the arch wiki. There it looked like they recommended downgrading the sof-firmware package to version 1.9.3-1, which I tried. The result was no change from the baseline problem: 3.5mm output works, but not the speakers.
A lot of the other discussion around those output lines seemed to be related to people having problems with audio resuming after system suspend/sleep. Their situation seemed inapplicable and following their advice to unload and reload the snd_sof_pci_intel_icl module didn’t produce any results.
I also gave the kernel parameter modification suggestion you have a shot, but level 1 did something similar to when I was on the LTS where I had different, but all non-functional devices. Level 2 didn’t detect any audio devices at all. And, level 3 produced identical results to my baseline configuration where I can get headphone/3.5mm output, but no sound from the built-in speakers.