I have a Sig P320 compact. For carry use, I use the compact slide on a subcompact grip module with no rail. (Still has 12+1 rounds.) I'm a big fan of N82 professional holsters for comfort and retention, but they don't make one for the P320. I've used their Original Tuckable, but the elastic means you have to basically remove the holster to re-holster your gun.
Ozarks Holster makes custom Kydex in many configurations, including the standard P320 compact or my Frankengun version. It is not quite as comfortable as the N82, but very compact and easy to re-holster during classes. It's also fairly easy to put on / remove while seated in the truck.
https://ozarksholstercompany.com/shop/kydex-iwb-holster/
I started out with an Alien because it was the only P320 IWB holster I could find at first, but I found the wide twin-clip style to be too bulky and uncomfortable.
BTW, some other Ram truck options: a left hand Hogue plastic holster that clips to the map slot of the center console and a Console Vault.
BTW, great gun choice! I love the trigger on the P320 compared my DA/SA Sigs. My other carry pistol is a Sig P938, which is SAO, 1911 style, carried cocked 'n locked, but only has a max of 8 rounds.