This free (I love free) Analiti test tool is available for Amazon's Fire TV and on the Google Play app store. It's one of the best I've seen, combining Internet and WiFi and displaying the results in a (somewhat) less technical way. As shown below, our home Internet and WiFi are in excellent shape. Spectrum is delivering on their 300 Mbps service and our home WiFi is capable of speeds that would allow for 8K streaming, thanks to our triple-hub Google Wifi mesh.
You can install the app to your Amazon streaming devices directly from the link below.