The circled part in red is what the actual serialized firearm is. Everything else is able to be changed or swapped. So you can swap out the grip to any other brand that makes aftermarket grips. I've chosen the
Wilson Combat grip modules for my standard p365 with the 3.1" barrel, and for my P365 XL 3.7" barrel. I do not have a Macro model technically, which really is just a full size grip module holding 17 rounds with a XL 3.7" barrel and slide up top. You can mix and match the 365's series, swap uppers and lowers. short grip with long slide, long slide with short grip, etc, etc.
Icarus Precision is another company that makes grips for the Sig P365 series, but they're too costly for me. On my XL, besides the addition of the WC grip module, on most of my guns I like to use
Talon Grips. It gives me my hands more grip on the gun. I choose the PRO version, which is a mixture between their rubber and sandpaper combined. It affordable and gives me the extra traction to grip the guns tightly. Depending on the conditions, how often to handle the gun, if you sweat on it alot, etc, they can last for 1 year to up to 5 years. Easy to install and take off. P.S. In case you don't know, in order of size it goes; standard p365, XL, Macro, Fuse. So the XL I have is the same length grip you have onj your "X" model, but my barrel is 3.7" and yours is 3.1" - and 3.1" is the same size that comes on the standard small p365 - it's just the standard p365 comes with a shorter 2 finger grip holding 10 rounds. It gets confusing when manufactures like Glock and Sig makes so many similar models, hard to keep track of everything unless you treat it like a part time job lol. Always happy to answer questions!