Yes, the previous company I worked at redirected the Oracle download pages to a custom page explaining the problem and offering alternatives. That was nice.
How bad was the problem that they had to set up a browser extension for this specific problem? It's not something DNS alone can fix due to HSTS
Yes, we redirect to Open JDK
Yep!
Our company does this too, but it sucks when you are googling for some info and it’s on oracle page. Still there is no better solution unfortunately