Satellite-based ISR support to Russia (or at least the Wagner Group) is allegedly already a thing according to the US. So if China wants, they can definitely expand their satellite-based ISR support to the Russian military through those already sanctioned companies. Besides, satellite-based ISR support is less visible and less open to the naked eye, so there is more clause of denialibility.
Regarding aerial-based ISR, I'm not sure how China is gonna keep it low profile if, say, one day, a Russian photographed a KJ-200 in PLAAF colours flying above Belgorod. So that's not exactly a good idea.
On the other hand, for ISR drones, WZ-7 would be a good candidate. However, Russia is not known to have AEW drones like the WZ-9 and JY-300, and considering that NATO members are looking to provide fighter jets to Ukraine, so I think they would also be a good addition. Though, I think significant training for Russian AEW crews are required if they are to be paired with the A-50.