One of TSBs refers to a DTC PO521 code using another GM/Delco oil filter part #UPF48R. That sounds like a far reach that a different oil filter is going to stop it from setting a code. However it's not going to cost a bunch of money to try it.
Then they talk about the screen in the oil manifold, which I assume is the screen you have mentioned.
There is also talk about doing an ohm reading on the oil pressure switch, which you already say you've replaced, but just because a part is new doesn't mean it's good. I can think of a few times new parts came out of the box defective. Just something worth keeping in mind before you tear your hair out chasing a non problem.
Have you put a mechanical gauge on it to verify what the oil pressure actually is?
A stuck by pass valve, weak or broken relief spring in the oil pump, could also cause it.
Checking oil pressure with a mechanical gauge would show an actual oil pressure problem. Then you have to hunt down the mechanical problem. I would want to verify that the mechanical portion was up to snuff before chasing electrical gremlins.
That's how I would approach the diagnostics, just my
.