whatever happened to the PSA 9mm ar kit?

They have them available on their website- not sure you what you mean by "So does anybody know what happened to it? Did many come to market?"
As for how well they work- I don't know but I will soon I think- my son is gathering parts to build one.

As much as makers churn products and introduce new ones, the feedback from owners takes time. About two years seems to be the usual.

Plenty of new gun introductions has gone on in the last ten years which are searchable on the internet. Early comments document the issues - or lack - the company response, if any, and the follow on acceptance, or not.

SIG P938 vs Remington R51, for instance. The early SIG guns used the .380 extractor and had issues, after about SN 85,000, no problem. Current sales are fine. R51? Not good. Considered a major disaster and worse than the Caracal.

9mm AR pistols sold as kits are going to take more time to complete, then the users to shoot extensively enough to understand what are the more significant issues, if any. The adventure for early adopters is that next year they can be the innovative owners who did the right thing.

R51 owners wish they could say that. We have to wait and see.

I bought a PSA 9mm rifle kit. The mag well adapter is plastic and non-adjustable. That said, it fits tight and I haven't had an issue. I have only shot about 200 rounds through it though. I also removed the handguard and a2 post and put a utg pro free float rail on it. I like that quite a bit. I also put the spikes 9mm buffer and a heavy wolff spring in it.

I have only shot it at 50 yards so far, but it does seem to be pretty accurate. I have shot both fmj as well as cast bullets with no issues.

I have only tried the PSA mags and also a midwayusa stoner mag. They feed ball ammo without a problem, I do get problems failing to feed about 3-4 per mag with truncated cones or hollow points. Some people have the same problem with more expensive 9mm AR's so I'm not too worried. Cast swc do feed without issue though.