The upgrade to Netbox 3.2 brings Provider Networks objects:
https://docs.netbox.dev/en/stable/core-functionality/circuits/
or:
https://netbox-next.wikimedia.org/circuits/provider-networks/1/
I don't see a huge benefit for this feature (eg. for automation), but it's easy to implement and will help documenting our infrastructure properly (eg. it allows adding X-connect and patch panel on the Z-side if needed)