Perhaps, or maybe the revenue generated by Android is so small that it isn’t worth the effort to change app stores.

You overestimate the size of the app store. It is big, but that doesn't mean the remaining 37% of app economy is small.

> iOS was responsible for 63% of total app revenue in 2021

Those numbers are global. In certain markets, like the U.S., that number is likely to be very much skewed towards iOS. Even if you look at the global numbers, iOS was responsible for 75% of app revenue once games are excluded, and 78% of subscription revenue in 2021.

https://www.businessofapps.com/data/app-revenues/

I think you could say the same thing with Steam. Developers are incentivized to publish on Steam because this is where they can reach the most players, even though they'll have to take a big cut for it.

It’s also apparently the same ballpark for video game consoles (which are also general-purpose computers that are similarly locked down to restrict third-party software).