It is a remarkable edc. I threw an XL wilson combat grip module on my 365 (original mags work if you buy new baseplates).it can, but, it is not worth it. if you want to do that to the sig - you can.
at price point of those guns, just buy one, then buy other, then sell one you will dislike more, of keep both.
eventually you will see why this is the only way.
ps. i own and like the original p365 as it is the smallest one and the - probably - best edc gun ever made. xl and larger ones have their fans, but kinda deviate from the point an original gun have made. depends upon of what works best in your hands.