From my own personal experience through a Google acquisition: you don't need to go through the interview process. We got calibrated to Google's system, and after that we were as able to move around as any other "real" Google engineer (read: people who went through the interview process.)

Mind you, YMMV depending on division you get acquired into and your position.

In addition to what /u/dguaraglia said, Google interviews are nothing like auditioning in front of a room of people, much less "Damores".

At least your options vested.

Agreed, that would be pretty irritating, but one would assume that the job offers come with significant salary bumps to compensate. They may also be trying to figure out what band to put you in. Google really protects their bands pretty carefully. Having a junior engineer in a senior engineer role can be pretty disruptive.