How do I make an embedded Android OS with just one app?

Question

I would like to make my own embedded system built on Android (ARM) just using devices distributed with Android but without their launcher.

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Answer 1

By the sound of your question you want to create your own custom Android OS build. That is going to be more involved than developing ordinary Android apps and consequently you're going to have to do a lot of reading, especially the Android OS source code.

I recommend you start here at the Android Open Source Project.