I've got 3 horizontal shoulder holsters.... one for a PPK (cool JB factor from the 80s) the others are Miami Vice style with offside double mag pouches......I use with Beretta Compact/Centurion and Sig 245/220.

Got them both "used" (not really)at local gun shops in the 80s/90s for
< $50each

High under the armpit works best IMO/ for me. Only time I use them is in the winter under a jacket of coat. Just pull the zipper down half way and grab the grip and pull. Kind of a handy grab and go set up for walking the dog.... gun and 2 spare mags. Coat/jacket locks gun against my side.