I brought up CGNAT because my American ISP does use CGNAT. We are now paying an extra monthly fee for a static IP, which I believe is the only option they have

I brought up CGNAT because my American ISP does use CGNAT. We are now paying an extra monthly fee for a static IP, which I believe is the only option they have for getting a public IP (i.e. no intermediate fee amount for a public non-static IP).