Wow, you can pave the way for all of us being that close to the heat :)
I am informed there is an Apple store in that 'spaceship', like an experience centre or such. Cute to visit one day.
When you would be in The Netherlands I would have been happy to link you with my Dutch senior AppleCare guy when possible. He's a total pro regarding their iPhones and iPads.
But being that close to Apple HQ you must have even more options to make yourself 'heard'.
Maybe take a deep breath and reach out to AppleCare by phone, explain all the steps you went through, explain that the problem is known by Apple (my previous iPhone 7 with a lot of supporting data is being/has been researched at Cupertino regarding this matter) and that iOS 11 would/should fix it, but you have tried and for your iPhone it's not the case, and that you want to have it fixed, and that you are willing to help where possible if they require info or want to do tests with the phone. Apple can do already very advanced stuff from a distance with your phone. When at a certain moment a senior AppleCare guy is connected with you, from that moment on you will only deal with him or her, and you will get his or her email address and you will be in touch with that person all the time, as it should (not everytime someone new to explain to).
Hope you can and will reach out to AppleCare by phone. Have a little patience at first with them because they may go through all te obvious steps first, and when they understand that you are an advanced user and the problem is indeed something deeper, I am quite sure you will get a senior AppleCare person specialized in iPhones and iPads appointed to you to work together on (y)our problem. Apple has to look at all the problems individually as so far known the problem with this problem is that not all iPhones 7 and 7 plus experience this problem.
Thank you ttttttaaas, I think you would be perfect to contribute in this matter as you are that close to Apple HQ and you seem to be an experienced user.