I have made this video to show how easy it is to use a website called APKPure to get APK App files to install just about any app there is. They also have an app themselves to help manage & keep upto date the apps you have installed.
You can use this app to sideload apps to Amazon Fire tablets (I am testing fire stick but not working great as I write this.) easily with out having much hassles finding the right apps & files and trusting that they are probably exact copies of the original released files from the app makers rather than possibly modified apps from untrusting websites & malicious distributors.
This I hope helps some trying to figure out where to obtain APP APK files for app they want exspecialy if you want to roll back to a previous version of an app that APKPure website has most of the older versions also for tons if not all apps that are in the regular Google app store.
I had an incident and so did many other few months back with even the top app maker Google and services not working after auto update. I waited a week for a fix then found APKPure website and bam! Problem fixed as I rolled back to previous working version with in seconds. Then few weeks later Google fixed the problem than I updated to the new working APP & services.