Foot exercises for outer edge foot and technique exercises

I don’t how to phrase my question better but a little bit about me, so you know where I’m coming from and what I struggle with.

I had an instructor for 2 days with whom I was also able to snowboard beside the slope in some powder or skiroutes (resort Lech-Zürs), however I’ve only snowboarded like 10-14 days my life so my “snowboarding” muscles aren’t developed (was in 2021 since then I’ve only been skiing again). I had pain in my outer edge of the left foot (I’m a regular) and he told me it’s actually a good sign since I want to have the pressure there where my little toe is/ begins. So I was wondering how can I improve my feet muscles during off season so I don’t have this pain anymore? I do bouldering regularly (3x a week 6c-7a) so I was surprised that my feet muscles aren’t so strong.

Also if you have good technique exercises, they’re always welcomed. I LOVE to improve technique haha