Its a hard resource-intensive problem to dogfood your own OSS at a company as large and diverse as Google. But hard problems haven't stopped Google in the past.

What you're trying to create is the same spark in your users as PHP and React did to the web. The "oh wow I could do...." that while technically possible before the product existed, is completely re-framed by relatively minor improvements to the DX. You want to inspire an entire generation that may have passed on mobile and cross platform app development due to the verbosity and pitfalls of the iOS and Android ecosystems.

I think a killer app example is the ticket to do this. It may not be the only way, you could blow a huge marketing budget, you could convince another large tech company to do it, but doing it yourself is probably the quickest (or only way) to get it done.

Maybe some android utility that doesn't need Google integration.. Let's say calculator app from next android version?

I mean... if we ported Android Calculator to Flutter, would that really impress or convert anyone?