The manual recommends Breakfree CLP.
The 197 ammo, mostly what I shoot, is pretty clean stuff.
I just use Breakfree CLP to clean and lube (I use it for all my guns). And, I use a boresnake to clean the barrel. Some people use a cleaning rod.
But, the Breakfree will work great and is really all U need.
I have solvent at home, but use it maybe 2-3x a years for certain guns - very rarely. The PS90 doesn't need it.
There is a polymer safe Gun Scrubber - it seems like it would be fine for the PS90 - but I wouldn't necessarily say to use it - because I really don't think U need it.
The manual says not to oil the trigger group or the inside of the mags. And, they really don't get dirty. And, you can actually rinse the trigger group off in water if you really wanted to. I've had mine for a year and just wipe the trigger group down with a dry rag to get any powder off of it. That's all ya really need to do.
So, I think for the PS90 - gunscrubber is overkill. Gunscrubber is great for spraying down into the frames of handguns - where junk gets stuck up in the trigger and the hammer area.
As for the PS90 - yes, it is kewl. I love mine too.