Unfortunately that did not work for me. The container Discourse runs in is not isolated from its host; the database, uploads, backups, etc. are stored in volumes mapped to the host file system. You need to copy those as well, and when I copied the bootstrapped container from another machine, I could not line up the file permissions between the users inside the container and those on the host.
See also the comments in the related thread Discourse in a closed intranet
Another issue is that the launcher script does upgrades (Postgress DB migrations, for example) when time comes to update the Discourse version.
With this approach, I can simply update the local copies of Git repos and base Docker images, then run ./launcher rebuild app and let it handle the upgrade correctly.