I just had to sideload b4a_bridge.apk shown in the B4A installation instructions, onto my new Fire TV 4K Max Stick, and I'm not sure if the app is the newest but it's slightly different than the one I have on my older Fire TV Stick. When I build my app from B4A and it sends it to my 4K Fire Stick, the progress bar goes across as usual, then an Install screen pops up but it looks different... the buttons to Cancel or Install are at the bottom right corner, and there is no highlighting. The sequence of buttons I have to press to get to Install are DOWN, then RIGHT. Luckily I can hear the clicks happening as I press the remote arrows, and when I point at Install there is a higher pitched click.
Is there a newer version of the bridge, and why hasn't it appeared as compatible in the appstore yet? I have channels published and went through those woes before and it usually involves setting the sdkversion parameters correctly in the manifest... maybe a few other tiny things on your store account, but there is no reason why this simple app can't be compatible with practically all Android devices so we can install it easier.
Thanks for getting back to me on this, and I realize this thread was old when I replied.