The ability to list-validation-sets via snapcraft went away in version 7.x. If I revert to 6.x stable, things work as expected:
# snapcraft list-validation-sets
Usage: snapcraft [options] command [args]...
Try 'snapcraft list-validation-sets -h' for help.
Error: the following arguments are required: snap-name
# snap refresh snapcraft --channel=6.x/stable
snapcraft (6.x/stable) 6.1 from Canonical✓ refreshed
# snapcraft list-validation-sets
Account-ID Name Sequence Revision When
YYYYYY test 1 0 2022-07-18