Welcome to the forum, dsa.
Like Boricua, I recommend CompTac.
CompTac makes this holster specifically for appendix carry. It takes a while to break in the extra leather at the muzzle. Adjust to your comfort with trimming. The C-Tac doesn't have extra leather to trim. Either way, the clips on wings are cool and you get the best design of combo kydex and leather.
As 10thmtn says, Onesourcetactical / Gabriel Suarez sells several appendix carry holsters. As this example shows, they have
clips on the holster. I think wings are better at dispersing weight and making for a smoother profile and a slimmer contour.
Appendix carry under an untucked short-tail shirt and a vest is my most concealable outfit. You don't want a thick gun belt with appendix carry because the overlap at the buckle adds at least another inch to the protrusion from the body. It's accessible standing or sitting.