The writing was on the wall, and now it's on Amazon’s website. Newly released Fire Sticks will not support the sideloading of Android apps or any other software from outside Amazon’s official app store.
The proof comes from an update to Amazon’s website for developers, which currently reads:
Starting with Fire TV Stick 4K Select [which came out in October], all future Fire TV Sticks will run on Vega.
According to the Internet Archive’s Wayback Machine, the website has included that statement since at least January. But Amazon hasn’t made this declaration so outrightly to consumers, many of whom are just now learning about Amazon’s commitment to its new, proprietary operating system (OS), Vega OS. Amazon declined to comment to Lowpass this week after “multiple sources with knowledge of” Amazon’s plans reportedly told the publication that all future Fire TV sticks would launch with Vega.
TechCrunch 
