There is an error with latest OpenNext using pages router's res.revalidate("/path") on latest Next 16. It will throw with an error: Error: Failed to revalidate /test/1: Invariant: missing internal router-server-methods this is an internal bug.
I wont have time to look at this before later, but I made the issue to track it. If anyone wants to dig into this feel free!
I made a minimal reproduction here: https://github.com/sommeeeer/opennext-pages-revalidate-invariant
Steps are in the README