I tried LXD once, but I can’t remember why it didn’t work. It may have been because of the need to setup the trust for the CA cert. Doing snapcraft build --use-lxd probably wouldn’t allow me to hack in the extra certificates like I could when using the Docker container.
Edit: Maybe the --shell option to snapcraft build would allow for adding the certificate, actually. 
I just have a lot of experience with Docker so this was the first solution I was able to get to work. 
I didn’t even know that was possible. All of the examples I’ve seen so far needed either multipass, Docker, or LXD.