Misfire?

Hello, if you have low compression on that one cylinder then it is most likely going to be a valve sealing issue, (burned valve, broken valve spring, or something worse like piston/ring damage). You can put about a tablespoon of oil into the cylinder and reset, see if the compression comes up, if it does then it's probably a piston or ring issue, if it doesn't it's going to be a valve issue. You can get that cylinder up to top dead center and put some compressed air into the cylinder and see where you hear it leaking out. I'll post some more info on testing for you.
If you can unplug the fuel injector for the number 1 or disable the injectors some other way so you don't get any cylinder wash while doing a compression test. If the vehicle has Clear Flood mode, you should be able to hold the gas pedal to the floor and the vehicle won't start, and if you have all the spark plugs still in, you should be able to hear an uneven cranking cadence or rhythm, it won't sound even, that's other indication there is a compression issue,
But putting some compressed air into the cylinder when it's on its compression stroke and the valves are closed with the piston at TDC, you will hear air escaping either into the intake manifold, out the exhaust, or out the oil fill cap meaning its escaping passed the piston into the crankcase.
You don't need to put more than 60 or so PSI of pressure into the cylinder, and if you have trouble getting the piston to TDC on the number 1, rotate the engine by hand with your compression gauge still on there and watch for the compression to start to rise, then you know you're on the compression stroke, from there, the harmonic balancer should have a mark on it for the number 1 cylinder.

https://www.2carpros.com/articles/the-reasons-for-low-compression

No not with such a difference in pressure from the other cylinders, that cylinder was misfiring already and if the injectors were spraying at any time during your testing that cylinder probably had some cylinder wash happening. Does your compression gauge have an air hose fitting if you take the gauge off the section that threads into the cylinder?
Some do where you can hook an air hose right up to it and put some compressed air into the cylinder and basically do a cylinder leakage test. If you have a smoke machine you can also get the piston up to TDC and put some smoke into the cylinder and see where it leaks out.

It would be best to do a leakage test to be sure it's a valve issue, a valve can be replaced, when a piston is damaged it's a much larger repair, most likely an engine swap at that point.
This is my compression gauge fitting; you can see the gauge comes off and it's an air hose fitting so I can put an air hose on it from my compressor for cylinder leakage tests.
The 3rd picture is an actual cylinder leakage tester you can get at Harbor Freight for around 70 dollars. But once you determine whether the fault area is in the cylinder head or in the engine block such as a piston or ring, then you can decide what to do from there.
Here's a quick video that walks you through the process. It's only 10 minutes:

https://www.youtube.com/watch?v=h993q16Oul4