They have little to do with each other. The lats are the primary movers in pull-ups, while they are only a supporting muscle in deadlifts.

Also if you are having general back troubles due to sitting, deadlifts are more likely to fix them.

Risk to Reward ratio. And no, deadlifts wont help with your sitting problems. Your lats are the ones that need stretching n that case.

Those work completely different muscle groups and are not at all comparable

They're both hitting the back. That's not a different muscle group. One is literally hitting the uppers and the other the lower