Meanwhile, an Android app for some random banking or government thing will require an attested boot chain measured all the way down to the stage 0 ROM burned in

Meanwhile, an Android app for some random banking or government thing will require an attested boot chain measured all the way down to the stage 0 ROM burned into the SOC. That's not to say the open ecosystem isn't better, but to say it's winning enough to guarantee sustained general purpose viability is simply untrue.