For something completely different, you might want to look at Unikernel Linux: https://arxiv.org/abs/2206.00789 You could run all the code without switching between userspace and the kernel, and you can call into kernel functions directly (with the usual caveats about kernel ABI not being stable).
There is a v1 patch posted on LKML, and I think they're hoping to get a v2 patch posted by January. If you are interested in a chat with the team, email me rjones redhat.com.
Fun! We have support for running on gokrazy (https://gokrazy.org/) already, and that's probably where Unikernel Linux is more applicable for us, for when people just want a "Tailscale appliance" image.
One of the authors here: it could, all the kernel code is present. Right now the android selinux policy blocks some of the necessary ioctls (at least on the pixel builds I tested).
There is a v1 patch posted on LKML, and I think they're hoping to get a v2 patch posted by January. If you are interested in a chat with the team, email me rjones redhat.com.