ONOS is being used with VOLTHA to enable PON networking in various locations (For example DT in Germany: https://convergedigest.com/deutsche-telekom-taps-open-source... , and IIRC it's also in production in Turkey).

There was a Comcast deployment to trial ONOS + whitebox switches a while ago.

The specific interplay of commercial deployment to open source vs commercial closed source in the networking space was better described in this post from Larry Peterson: https://systemsapproach.org/2022/02/28/venn-diagram-engineer...