We were just discussing this (jump start) in another thread...
Some jump packs (like the NOCO ones) also have a button that forces them to output voltage even if they don’t detect anything on the other side. That will usually solve the problem.
That said, if the truck sat for a month, then started and didn't run long enough to fully charge, then sat in the cold for a few days... The battery charge should sort it out. IMHO, GB40 is WAY too small for that diesel. Also when you jump, the IBS (intelligent battery sensor) needs to know there's a good charge state so jumping on the battery terminal side blinds it and may prevent crank.
The Noco GBX155 is currently $337 on Amazon. Buy once, cry once.