"This effort demonstrates that with the right design and optimizations, Azure PostgreSQL can be scaled to handle the largest production workloads."

Sure, but choosing from the start a DB that can scale with ease would have taken far less time and effort.

You can bend any software into doing anything, but is it worth it?

They could've just sharded it; their users are not interconnected, it would be easy to just have 128 shards and then assign user to one by org/user hash