Filtering out hosts by ansible_facts that do match some condition is tricky from an implementation perspective. We would need to ensure that the GIN index that we use in Postgres is still being used. That is one of the reasons this feature doesn’t exist in AWX today.
I use the API directly when I’m constructing host_filter. You can “test” your host filter on the /api/v2/hosts/ endpoint. When you have what you want you can use the API to save that filter i.e. navigate to the browsable API via /api/v2/inventories/3/ change the json host_filter value to whatever you have crafted and click PATCH.
/api/v2/hosts?host_filter=ansible_facts__ansible_distribution=CentOS <— this would create an inventory WITH CentOS hosts.