Looking at the Release Notes Community and Upgrade Process in the documentation I see no mention whether OpenNebula CE can be upgraded to 7.0, and whether the non-public opennebula-migration-community packages are still provided/required.
OK, found it just after posting the above, it is in the announcement:
Migrator Package Now Included for Community Users
As part of our commitment to broadening access and simplifying OpenNebula adoption, version 7.0 now includes migrator packages to upgrade from version 6.10. This enhancement streamlines version transitions, making it easier for community users to stay up to date and take full advantage of the platform’s latest innovations.
Maybe the Release Notes Community page should mention this as well. Anyway, sorry for the noise.