Hi I'm an Australian PowerApps ISV and we deploy our advertising industry-based solution into an environment created in our client's MS tenancy. This is the first one with multi-geo enabled.
We also have an Office Excel add-in that connects their planning files (a range of proprietary/bespoke formats) into some tables in the PowerApps environment via PowerApps WebApi. 99% of the time it works with each user's credentials no problems. The only ones we're having difficulties with is some users out of Europe they're getting a message from the add-in's OAUTH flow that is typically associated when an AAD B2B guest user tries to access the WebApi. Through the frontend, no worries but directly through the API it doesn't allow you to authenticate.
I know PowerApps isn't a multi-geo aware service. The evidence points to multi-geo tenancies being several separate tenancies under the covers with a veneer of cohesion over the top, is this right?
What I'm trying to find out for PowerApps is exactly what limits there are for outside-geo users in a multi-geo tenancy?
Do I treat them as B2B guests?
What limits of accessibility for the WebApi are there for B2B guests? I know you can access PowerApps as a B2B guest through the MS-provided frontend but not directly through the WebApi, but what else is there that I need to be aware of?
Is there some documentation for all this out there that I've missed? I've searched a LOT though.