If it's testing hardware, then why doesn't it have a replaceable battery? This is just madness.
"At $19, it's probably being subsidized substantially."
Doubtful
> this is a toy for devs to get to know their stack...
The difference being that AWS has real tiers. The dash button is exactly the same even if you "go pro" (what does that even mean? You persuade your BigCo employer to join the program?).
I suspect it's a last-gasp attempt at making some money out of a program that has not become as popular as they thought.
In the same way free AWS instances are not adequate for hosting a production website, this is a toy for devs to get to know their stack...
The real question for this device is, is it hackable, i.e. can you change the software running on it, or open it up and solder different hardware to spare pins?
It looks like people have done this, but it's surprising amazon would sell a devboard without catering to it: https://github.com/dekuNukem/Amazon_Dash_Button