1998 Jeep Grand Cherokee, No compression on #1 Cyl,

Could be the valves, rings and cylinder wear-I recommend you get a cylinder leakage test to confirm where its leaking at

leakdown test?

You can do a wet compression test, that is add a small amount of oil into the cylinder 1 tea spoon is plenty are re test comps, if comps come up it will be faulty rings, if not valves, the oil will seal the rings for the test so if comp is lost via the rings the comps will come up, the excess oil will burn off when you start he car up again.