A good choice if you want a few more rounds - Tyrant CNC Snub Nose Sig Sauer P365 Grip Module

Good choice if you want a few more rounds (17) in your standard P365.
Comes with a medium and large replacement back strap, no small. When you swap them, watch for the little nut inside the one that comes on the grip. It’s tiny and will fall out when it’s removed. You will need it to insert in the other back strap to swap it.
If you have a manual safety you will have to cut out the notches on this grip. They have marked an outline on the inside so you can see where to cut/grind/dremel/file so no guessing. Just take your time, go slowly and keep checking the fit.
Of course you will need new (expensive) mags to fill the hole.
Only thing that would have made better, is if it came with a small back strap like the X Macro Comp does.