I have been carrying a gun for work or self defense since 1994, and I think the PHLster
https://www.phlsterholsters.com/shop/phlster-enigma/ holster chassis system is probably the best appendix inside the waistband system in current production.
It is designed to be used with multiple manufactures holsters, but allows users to carry in sweatpants, gym shorts, and any other type of clothing.
I am using the chassis with a JMCK holster and I can carry my RDS equipped G19 while exercising, working, and doing chores around the house (I wore it while I push mowed just under an acre today).
One of the only negatives is that it is a little pricey and is hard to get, the sell out quickly.