So this unit has the freezer on the bottom and the fridge up top.

I have checked that the compressor fan works as does the compressor. The compressor is hot to touch as well.
The defrost timer switch will put the fridge into defrost, however I was unsure how to check the internals with a multi meter, so unsure if the timer part is functional.
Defrost thermostat was taken out and tested both at both hot and cold temperatures and shows continuity at cold temperatures.

The only thing that I could visually see is some dust build up on the bottom of the freezer, and it has been cleared. Also, the freezer evaporator was not chilled, though there was massive ice build up around the thermostat and pipes leading to the evaporator coils and fins, though only there.

The seal on the freezer unit is shot and will need to be replaced for sure, however the refrigerator seal is fine.
I did not test the evaporator coil fan.

So, I'm trying to determine if the unit is low on coolant, or if the seal on the freezer is the culprit for both the freezer and the refrigerator not cooling. After doing the cleaning, and defrosting the ice build up on the thermostat, the unit did get cooler, however, it's maintaining at around 40 in the freezer and about 60 in the fridge, and they are both at the coldest setting.

I'm not sure what to test next, or how. My gut is telling me to look for a coolant leak and refill. Even with the poor seal on the freezer, it was operational.

If anyone can provide me some tips, I would greatly appreciate it.