Seated Military Press is fine, and likely better for growth because of the extra stability allowing you to push more. Standing comes with a lot of it’s own benefits but ultimately it’s your individual goals that matter. As above said, 5/3/1 can be applied with any exercise. At it’s most basic form, it’s just a progression method for your main movements - which could be anything.
Did you ever implement seated overhead press in your training? The cold weather has me considering moving my gym from my garage to the unfinished side of my basement. One has enough space to press, one does not.
I did. It worked out fine. The main difference is I can lift less with a seated press. However, when I get to my gym I found my standing press press still went up as I’d built strength from seated. Only other difference I can think of if seated press works the core less. But I normally get a 1 m weighted plank in at the end anyway.