Oh, I know this one! Make sure you’re using pipewire and use HDAJackRetask. You can reassign the ports to whatever, you can even swap mic and headphone if you want.

This is literally on the road map for GIMP, right up top. (Status: no just means it hasn’t been started yet and isn’t planned for 3.2, not that it isn’t planned) https://developer.gimp.org/core/roadmap/

I was thinking not only about the finicky drivers, but also the different audio backends, like ALSA and OSS, Pulse would have just come out at the time, so it was definitely getting better, but it was fresh off the presses back then, so it wasn’t good enough yet either. Nowadays, Pulse works pretty well, pipewire works pretty well, things more or less just work, Bluetooth can be a little weird, but usually you just need to change the settings on pulse/pipewire to your preference.

Audio and networking were a shitshow back then, nowadays almost everything just works on those two fronts. Also, having to edit your Xorg.conf is not what I’d call user friendly…