Thanks so much William!
Regarding "user in the container needs to exist and have matching uid/gid" - that is fine and we will handle it on our side.
Please let me know if you'd like me to do any testing once the issue is fixed :)
If you have any doco also regarding specific config to make it work, that would be good too. e.g. update to any config file or is it enough to run dscontainer as the unprivileged user?