There might be some older posts, but I could not find any recent reports on the business OW lounge at PVG.
Has anyone used it recently?

The situation is more complicated now. When I was there last, OW airlines were split between T1 and T2. So it depends on which terminal you are departing from.

And in general most lounges at PVG are actually contract lounges operated by the airport and not by the OW carrier.

The CX/KA lounge was moved to T2, but I don't know about the JL lounge. If it is still in T1, then both terminals have OW lounges.

I would be flying SFO-PVG on 9W (for miles) arriving at 02:30 and connecting to CX to HKG around 8 AM.
Would the lounge be open?

I am not sure anything is open at PVG at 2.30. I have used the early CX flight to Hong Kong a few times and arrived at the airport when literally everything was closed. However, the lounge is the Dragonair lounge. Don't be too much disappointed. This lounge is some kind of a disgrace. You might be forced a long march to reach your HKG gate from that lounge which was at the far end of the terminal during my latest flights out of PVG

Sounds like 2-3 days layover in Shanghai would be a better choice.
I will only take this flight if I cannot get either CX or JL flights to SIN as the connection is so bad on 9W to CX. Otherwise I think 9W business class looks good.

According to CX web page, the lounge opens at 6am. If you have not toured Shanghai before, it is worthwhile spending a few days there. You can also spend 2-3 days in Hangzhou and Suzhou.

I assume this is referring to the old terminal - now with the new terminal since 4-5 months ago the CX/KA lounge isn't that long a walk from the immigration/customs anymore (although then from the lounge to the gate it could be a long walk - but could also be quite close).

We have been to Shanghai twice (first time in 1985, second time more recently with Hangzhou & Suzhou)). There is always something new to see or do or a new restaurant to try.
I just don't want to hang around for 5 hours in the wee hours of the morning(after a very long flight), especially if no lounge is open.

The lounge is at the far left end of the new Terminal, ain't it? And I had my latest HKG gates at the far right end of the Terminal. And the conveyor belt ran from passport control in the direction to the gates only. This was close to 500 meters...

umm I'm actually not 100% sure of the layout of the whole new terminal...but I usually walk a bit towards the left after check-in, go through immigration and security, and the lounge is almost right there already (a bit more to the left) - it's definitely not to the "far left end" (at least compared to the old terminal). the lounge is around gate 68 if I remember right and the furthest left gate is ~58, and I was quite lucky in having my flights the past few weeks all around 63-68 or so...so it wasn't too long a walk.

I think this is already much better than the old one where the lounge is very very far left...and often your gate was just right after you passed through immigration/security and you don't want to walk all the way to the left and then back to the right again. at least now the lounge is right there (with a bit of walking) once you get out of immigration/security (although yes, the flight can still be very far away - but I guess this could happen in HKIA or many other airports too).

unless...the new PVG terminal is like the HKIA, where there's immigration/security in both the left and right ends (south and north in HKIA), and you usually use the right one while I use the left one ?

Well, there is. And the mistake I made twice is to use immigration close to my gate. That made me walking from one end to the other and back again. However, I have changed my habit and now use the old aiport again as much as I can - by far more comfortable and quicker to get through.

The CX lounge is a bit "left" of the security entrance.but not much. Very good CX standard and better than anything PVG has ever seen.

But is it open from 02:30 when we arrive till 7:50 when we leave?