Wish they didn't. DIY opnsense/pfsense boxes are much harder for finding compatible NICs because they're on BSD. Conversely, used enterprise-level NICs often have better drivers on Linux than Windows.
usually if it doesn't have good working drivers on BSD, there's a good reason and it's probably better that you didn't use that hardware in the first place. if it was a well-established, reliable adapter then typically it would already have a driver.
How about an HP NC523SFP? Keep in mind, this is HP enterprise stuff, not consumer level. Dual SFP+, pulled from server hardware. Doesn't work on FreeBSD.