Installing an app (.apk file) from the native Android HTMLViewer 8.1

I have a tablet that's locked up pretty good (Android 8.1). Locked bootloader, managed android OS, proprietary apps, etc... I'm trying to see if I can get an app to install on it. One way I've thought of is through the Android HTMLViewer (version 8.1). The tablet has a help file that's HTML, which opens with HTMLViewer. So I tried throwing an apk file in the same directory, and seeing if I could modify the help.html file with an anchor tag that points to the apk. I've tried the following: download download download download Each one gives that same result. The viewer simply tries to parse the file and gives me a huge jumble of whacky characters. I thought about writing a small script in Javascript utilizing the FileReader object, such as this . However, I'm quite certain that HTML viewer is so slimmed down, it probably doesn't support this object. It is compatible with jquery, so I suppose there is some hope for this. Any ideas on how I could tweak this to accomplish my goal would be greatly appreciated.