So, I have made some progress in this direction in various ways, most notably genie - https://github.com/arkane-systems/genie - which lets you run systemd as pid 1 under WSL 2, and by recompiling the WSL 2 kernel to include various needed options, as documented in https://gist.github.com/cerebrate/d40c89d3fa89594e1b1538b2ce9d2720 .
These two have been enough to get snapd up and running, and the lxd snap installed and inited, networking/lxdbr0 included. Still having some trouble launching containers (the operation not permitted trying to mount sysfs error), though.