What's the issue with dual external displays? I ask because I'm using the built-in display on my 16-inch MacBook Pro (macOS 11.3) as well as two 27-inch 2560x1440 displays as I write this.
You can workaround the issue with a Displaylink dock though. I've been using the Dell D6000 dock to run two displays on my M1 Macbook Pro since launch. It's definitely not a perfect solution (with buggy wake-from-sleep quite often) but it's a good compromise until there's native support.
I would be really curious to see the source for this.