This just started last week; I changed the oil & filter today cause previous owner said it did that to him when he was late changing the oil/filter. When I backed into my drive, the light went out

Could be the engine, until the overhaul, was run on a low grade or low specification oil that allowed or even encouraged sludge and carbon to build up in the engine.
If a high detergent oil was used at the overhaul it would have scoured the inside of the engine, removing deposits so increased oil consumption is often the result.

The additive packs of some oils also tend to cause the premature hardening and failure of some types of rubber seal, though this was a huge problem 20-30 years ago it isn't seen much today.

Better have her take it to a shop before its too late. Could be the wrong oil or filter, could be sludge, could be worn bearings or journals, could be oil pump clogged up or weak. Could be nothing, just cold. A good running engine is worth an early diagnosis.

When was the last time that you had the transmission fluid and filter changed? This is the cheapest thing to try first.

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Inspect your oil control valve, disconnect it and read the ohms resistance, specs 6.9-7.9. If is not in specs replace it. it is possible oil change caused it, TIP: after market filter will cause engine damage,

well so if i understand right you have no oil in the vehicle? or have you checked the oiil dipstick, GM is known to burn oil so if you go alot more than three thousand miles between oil changes than that will cause the oil to burn off and cause the lights to come on, or you might have a leaky filter or drain plug and its loosing oil, so first pull he diptick check level and if you need oil just go get an oil change and they snould let you know of any leaks there may be

An easy one, finally.
The oil pressure sensor is one of the least reliable parts of any car and yours is bad. They are supposed to turn on the 'idiot light' at ~ 4 pounds of pressure which is almost too late for any warning since oil pressures range from ~30- ~60 pounds in most engines.
These are common failures and not costly to replace. Once you know where it is, with an appropriate wrench, it's about a 5-minute job.

Right away. Since ignoring an oil change requirement could cause an engine damage.

I have a gmc envoy (same thing) and it does the same thing. normal.

If your catalytic converter is "below efficiency" or otherwise clogged, you will lose power as you drive and the vehicle heats. The more you drive the vehicle, the worse the problem will become. The exhaust can't escape properly through the catalytic converter, therefore your engine won't run properly. Your issues are related, and if you replace your catalytic converter they should go away.