[llenotre]

There have been attempts to create kernel-agnostic interfaces for drivers such as: https://en.wikipedia.org/wiki/Uniform_Driver_Interface

For my case, I am planning to re-implement them. I like doing this.

I sure am not going to be able to re-implement everything myself though. I will concentrate on what I need, and I will consider implementing others if anyone else other than me is willing to use the OS (which would be incredible if it happened)

[seastarer]

You can implement a virtual machine monitor (e.g. KVM) and then launch a Linux virtual machine to run drivers you lack.

[joveian]

Or NetBSD drivers via rump:

https://github.com/rumpkernel/wiki

[pjmlp]

Or try to adopt Fuchsia/Android model of userspace drivers, maybe there is something to be reusable from them.