I also have a P365 X Frankengun with a SIG AXG frame. It's an early P365 FCU with a newer P365 slide with an optic cut and an AXG P365 X grip module.

Recommendations would be appreciated. I prefer to carry OWB, but if the holster were convertible to IWB, I wouldn't complain.

What do you like and what has worked for you?

I'd reach out to Werkz for confirmation on your specific setup, but I've been very happy with their OWB on my P365X w/Streamlight TLR7-Sub and optic cut.

Werkz OWB

I bought this one. Pretty happy with it, and I like the way it really hugs the body, but I'm not the biggest fan of kydex.

I've also ordered a leather one from Wright Leather Works. . They've got an about 8-10 week turnaround time so I haven't received it yet (another week or two).

SF member Ryan Grizzle ("Country Boy") made me this Georgia Snap 2 (GS2) OWB holster with elephant hide. Very comfortable, practical (especially if you need to use a public restroom and want to be discreet about your CCW), and beautifully made.