If your title was Chief Architect then accomplishments like this are baseline expectations for an IC, and your comp would have reflected that. It would have been well into 7 figure territory.
That said, Alex's title appears to be principal engineer at GitHub, which is roughly equivalent to principal at Amazon in both expectations and comp. I worked at AWS for just shy of six years, and I can tell you that the person who created Firecracker -- which underpins huge portions of AWS's technology -- was at the same level, and while they were promoted shortly thereafter, they didn't receive a bonus (because comp packages at that level don't include bonuses at all). So, yeah, Alex is justified in sharing these details publicly, but this is just how it works in tech. (And, frankly, all the underpinning infrastructure that supported him wasn't his work -- he might have come up with Copilot, but would he have been able to without the work of thousands of others?)
He leveraged massive resources to do it and was allowed to tap people with multi-decades of experience (even implicitly - you think he build the execution engine where his "test harness" ran?). Not to mention that he essentially wrote a wrapper around an API..
If he put his total comp this pity party would shrink to one.
No matter the accomplishment, I doubt they would have been able to create copilot outside Microsoft and thus without Microsoft’s resources (computing infrastructure, engineering talent and software ecosystem).
And the “join a startup” is a dumb piece of advice as you’d be still making some one else profit.
Create your own company, and face the likelihood of bankruptcy.