Found a cheap Pontiac Bonneville, but it has an oil leak. The seller says that it is the oil filter housing / adapter, but that doesn’t seem like a common leak in according to the internet, attached pic shows the leak.

My questions are:

Can it leak from here?

If so, how hard is it to remove the housing and replace the gasket?

What else could it be other than that?

Oil pressure sensor is above that. They are known for leaking.

So it'* probably not the oil filter adapter?

Eliminate the sensor first. Just reach in there and disconnect it. If the connectors are full of oil, then its a good bet that'* where your oil is coming from. The sensors are very known for leaking.

So if there is oil in the connector, the oil pressure sensor is 100% the problem?

I didn't say that, I said eliminate it first. Its easier.

Replace the sender.