Amazon announced the availability of the latest Fire TV stick yesterday. The Fire TV Stick 4K comes with a new remote that Amazon says is optimized and VegaOS instead of Fire OS.
The latter is what tweakers will find problematic. With Fire TV sticks using Fire OS, which is based on Android, sideloading was possible. You could install Android apps such as Smart Tube on the stick to gain access to features that apps in the official Amazon Store don’t offer.
With VegaOS, that bridge is burned. No more sideloading, which means that you are stuck with the apps that Amazon hosts officially on its store.
You find the usual assortment of official streaming apps and other apps there, but the store lacks apps like Smart Tube that you might want to install on your devices, for example to watch YouTube without ads and unpleasantries.
Anyway, if it has to be Amazon, stick with the previous Fire-OS-based sticks like the 4K Max, which is currently discounted in many regions as well.