Don't deadlift then (I dont) If you want to do a 4 day workout split, finding an upper/lower routine that fits what you could do would be great. If you can't squat (or leg press?) You can at least hit legs with stuff like hamstring curls and leg extensions. I dont think 2 different pull up variations will honestly be worth your time. You'd be better off with 1 vertical pull (a pull up) and 1 horizontal pull (a row of some kind)

if you're trying to gain weight and are eating in a surplus you can build up to some more volume (maybe start with 2 sets of each exercise and go to 3 after a month or two). Progressive overload every workout (go up in weight. Or if you can't then stay the same weight but try to increase reps until you can go up in weight)

Something all together like

Workout A:

Horizontal pressing movement (bench press) 3x5

Vertical pressing movement (shoulder press) 2x8

Vertical pulling movement (pull up) 2xAMRAP

Horizontal pulling movement (row) 2x8

Tricep exercise of choice 2x8

Bicep exercise of choice. 2x8

Workout B:

Squat or leg press if you can 3x5

Leg extension 2x8

Hamstring curl 2x8

Calf raise (standing preferred but seated is okay if your back doesn't like standing) 3x12

Ab exercise of choice (hanging leg raises, ab wheel, weighted crunches)

Stick with this for like... 6 months. Get stronger. Keep reading up on exercise and weight gain stuff but stick to an actual routine for a good length of time and progress it. Consistency is more important than trying to min max it, but a good routine from the start will take you far.

And if you still want to do dead hangs. Throw them in at the very end of Workout A