@jpm @whitequark it used to be LXC for low-level container functionality (a bunch of CLI tools with a bunch of logic on top of kernel containers interface) + LXD on top of LXC, for nice UX to manage the containers.
Then Ubuntu did a takeover of LXD, so incus was born as a libre community fork of LXD.
But incus still uses LXC under the hood, and e.g. on alpine LXC is still a dependency of incus: https://pkgs.alpinelinux.org/package/edge/community/x86_64/incus
I'm not sure which LXC tools are you referring to or how or why linuxcontainers dot org would refuse service to them (seeing how LXC is still listed there https://linuxcontainers.org/lxc/ ) or which LXC commands are you referring to.

Introduction The image server at https://images.linuxcontainers.org has been in operation since early 2014, first offering images to LXC users through the download template and then once LXD came around, it was expanded to also provide LXD container and eventually virtual-machine images. The infrastructure used to build and distribute those images has always been purposefully kept community owned and operated. That’s so that every distribution represented on the image server is on equal footing...
@whitequark so it turns out the folks who run linuxcontainers dot org have basically told canonical to play hide and go fuck yourself and blocked container image downloads from LXC tools. Theres a very simple LXC-to-incus migration script available, and then everything just keeps on trucking after you change lxc to incus in commands lines.
Also, nested containers works, I’ve got podman running inside an incus guest without elevated privileges.