While Google is making the change and 100% responsible for the mess, the work to understand the impact and adapt to it lays on the application devs and users.
I don't think there's any reliable way Google can properly guide users to deal with apps they don't (and shouldn't) control. You and me would be properly horrified if Google could dictate how Outlook auth works and what exact steps will help the user transition, whatever the Outlook team decides to do on their own.
The most they can do will be to help the app developpers to prepare for the change, and vaguely gesturing at users about potentially impacted settings.
I don't think there's any reliable way Google can properly guide users to deal with apps they don't (and shouldn't) control. You and me would be properly horrified if Google could dictate how Outlook auth works and what exact steps will help the user transition, whatever the Outlook team decides to do on their own.
The most they can do will be to help the app developpers to prepare for the change, and vaguely gesturing at users about potentially impacted settings.