So just for context, before knowing how to do this i would either right click the group layer and use layer styles to add a stroke thing but with a nasty circular anti-aliased stroke, or i would manually draw the outline using my brushes, so i just learned i can use selection tools to select my lines to then do Edit > stroke selection and pretty much get most of the job done

Then i just do and erase some lines here and there for a nicer and imperfect look, this is optional but its nice for me

btw yea this is iggy, he's fun to draw for this kind of testing stuff