Just to complement the answer of @simos for n00bs like me: for cloud-init to be used in the container (and so for the profile to work properly), one must use a /cloud image from http://images.linuxcontainers.org/.
See also:
Warning: for people who moved from LXD to Incus like me, ubuntu: remote does not seem to be available in Incus (only images:). ubuntu: remote had images with cloud-init while for images: remote, one must pay attention to picking the cloud and not default image