Motor knoking when oil light comes on

indicates what you suspect
the noise could be sump pressure trying to pass the faulty PCV valve and pressure in the sump will blow oil out of weak seal and gaskets

Oil light is rather important it goes out if oil pressure is good comes on if oil pressure is low when it comes on damage is expected with continued operation like wearing of main bearings and pistons and cylinders can lead to a engine rebuild

Somtimes drive belts can get a hard spot in them causing all sorts of funny noises. If the noise is related to engine revs, try removing the belts to see if it goes away

90psi compression is low in some cases engine may run but will be very weak and stall after a short time. a good petrol car compression should be between 120 to 150psi.
Does the engine oil light turn off after started, make sure u have oil pump up to the head, check the oil pick up inside the sum. The engine valves should not and never bend from no reason.

Not a vacuum hose. If it is coming from the top of the motor, I would first check the oil. If there is a hole punched into the oil pan , you may be very low on oil. If oil's fine, I would suggest looking at the transmission housing. If the manhole came up and hit the housing, it may have cracked that, or cracked the fly wheel. One more thing I'm thinking is that if the manhole hit your starter, and pushed it up, It may have cracked the fly wheel. This can make it sound like it's at the top of the motor. Very loud tap tap tap tap. If you excellerate, the noise will go faster too. I just can't see a manhole doing any damage to anything in the top of motor. Make sure you check the oil ASAP. Hard to tell without hearing it. A video would even help. Let me know what you come up with. Good luck

the oil light comes on from loss of oil pressure, this can be from two things 1. your oil pump is bad abd 2. your bearings around the crankshaft are bad. If the noise is coming from the bottom of the engine, Then the bearings are bad. If the noise is at the top then this could be the distributor. the distributor drives the oil pump, there is a shaft or a pin/tongue on the bottom of the distributor. See if it is broke. Also look down the hole and see if the pump is broke. It's hard to see but you can with a good light and mirror. Just a note, If your truck has had a knock for a while(like when you start it in the morningand it goes away in a few minutes or seconds) Then the bearings are bad. It's time to rebuild or replace.

It sounds like you have internal engine damage.

Certainly have the a scan of your computer done to find the fault codes for the check engine light. This will help you proceed.

As far as the oil light, Usually indicates low oil. make sure your oil level is correct.

is it more from the front or back of the car ?? over bumps ?? while acelerating or braking ??

on the top of the front struts there's a rubber bushing called the "upper strut mount" this is a commonly replaced item. Also the sway bar bushings are frequently replaced. or, it could be something totally different..... gremlins ??

It sounds like the lifters are draining down over night. When was the last time you changed the oil? A fresh oil change may do the trick, if not try some hydraulic lifter additive ( you just add to the engine oil)