Here is a screenshot with the Criteria for our Smart Group.

That was stupid simple, thanks! 

You can make it even simpler:

True, this will also work, but I preferred it to be future proof for this fall. ;-)

I'm using "Operating System", "matches regex", "^11" - which means it has to start with "11"

I found this works as well...

Apparently, it's not working for Ventura smart groups yet - at least not with the beta installed?

I've got a test machine, with 13.0 beta 8, and none of the above descibed methods work... So it never turns up, no matter whether I use @awoodbury's solution (greater than or equal 13.0), or the regex one, etc. First I thought: maybe Jamf Pro interprets the beta versions as lower than the regular 13.0, but it should at least be shown when using "greater than 12.6"; doesn't seem to be the case though. Any ideas?

EDIT: it could in fact be an issue with the relevant machine; it was deleted from Jamf some time ago, and just today added back (test mac)... I'll check first, if it turns up tomorrow and if not, reimage it + check again.