My guess is that like they did with Google, with time, Oracle will go after all the OpenJDK derivatives.

To be clear the licensing appears to be open enough so that this shouldn’t be a real threat, but IANAL.

Coretto passes TCK (as well as RedHat and Zulu, amongst others out there), there's nothing to sue for.

I'm sure it will be priced at just below the cost in legal fees to defend yourself..

Google did not have an OpenJDK alternative, they had a implementation of a language and stdlib that was 99% identical to Java.

Oracle owns Java. Amazon just builds its own version.