TL;DR: it’s probably not that hard to pick up compared to the complex and deep stacks we use today.

COBOL is in a special place in our computing legacy. It’s too new to require intimate knowledge of the electronics that drive it (older systems and machine-code did), and is too old to be all that complicated (target machines were much smaller and slower). I would wager it’s actually not that hard to learn, and is probably a dream to code with modern equipment. You won’t be slowed down by punchcards, tape drives, time sharing, etc., and can probably use VSCode and an emulator to cover a ton of ground. The computing model is likely a straight line (storage -> compute -> storage), with little to no UI. In other words: simple by today’s standards.