You mean configfs? Please take a look at my proposed gpio-virtuser

Oops, yes, configfs.

module, it should do what you want:
https://lore.kernel.org/linux-gpio/20240613092830.15761-1-brgl@bgdev.pl/ (local)

Thank you! Exactly what I was looking for. What I like is the symmetry
of instantiating GPIOs in either DT or configfs. Very elegant for the
user. But boy, this is a lot of non-trivial code for it.