I am using system-wide installed systemd user services to run some maintenance stuff in the user session.
Currently I am not able to manage this with the Puppet service resource type (or I did not find any related documentation or discussion)
References:
Adding a "scope" parameter to the service type is not too difficult, but the tricky part is making sure the "scope" is part of the namevar (so that a user and global service with the same name don't conflict).