Tried Pillars on PS4, I'm playing on PC now in a PotD run with companions.
Companions on PotD: Companions can handle PotD difficulty just fine, but you do want to put some thought into how you're building out your party for synergies. I'd say at least one tanky character, one back up tanky character, 1 or 2 for Crowd Control, and some good damage output, both single target and AoE. There's enough characters to fill this out nicely. Using choke points or single pulling (peeling off) monsters is highly recommended. Even so be prepared for some unexpectedly hard fights.
PS4 vs PC: Honestly PC version is way better here. The PS4 version is good, and they really did a good job on the controls for the most part. But using the inventory is tedious because it involves a virtual mouse. Also the PS4 version has some bugs the PC version doesn't, is behind on content updates, and seems to be no longer supported in favor of the upcoming Deadfire PS4 release.