I wish I was good enough at programming to write drivers for unsupported devices. I prefer illumos-derived OSes for servers (currently SmartOS) and it's difficult to map devices to this list https://www.illumos.org/hcl/. In a better world, I'd just buy the network card I want and write the driver. Even if I can buy a supported device, there's a difference between being able to pass traffic and supporting all the features. Nvidia ConnectX-6 is supported, but with offloading? SmartNIC stuff?
illumos HCL - WIP

Oh. There's a very helpful guide for porting FreeBSD drivers to illumos. https://docs.smartos.org/porting-network-device-drivers-from-freebsd/

I need to try this for the "ice" driver https://www.intel.com/content/www/us/en/download/19631/intel-network-adapter-driver-for-800-series-devices-under-freebsd.html. I have an Intel E810-XXVD2 (25Gbit network card) that I could try to get working.

Porting Network Device Drivers from FreeBSD - SmartOS Documentation

@JonathanGerlach
If you'd go that path, some bits from these videos might be useful:
https://youtube.com/playlist?list=PL3oXECC9Rpm03y_4HSaV6omSctF9__QyN
https://youtube.com/playlist?list=PL38E9D8BB8E71A73C

And, if you're up to that and not there already, feel free to visit #illumos and #smartos at LiberaChat IRC

Developing Solaris Device Drivers

YouTube