Using classic Outlook for Windows in business environments
Gabriel,
I would suggest you and team validate any procedure using an actual Android device. I think minimally a few late model Google Pixel and Samsung Galaxy devices should be checked along with iOS devices. If the Exchange service module on those devices aren't working correctly with MS' consumer emails' OAuth mechanism, then I think there is value for MS to work those issues out with said vendors. These are not obscure brands, and there are a lot of exposures in the real-world.
While Outlook for Android/iOS may work for some, it may not be an ideal solution for others, so there should be a reliable method to provide a single-point of sync for emails/contacts/calendars, EWS/EAS or successors.
Again, I don't think any of us is asking MS not to implement newer and safer authentication methods. We are asking you provide a way forward and validate OAuth on a few alternative client options.