The version of the Android Emulator you are using doesn't support webGL or webassembly. This is an issue with the Emulator not the runtime, all modern Android devices support those features.
When possible we always recommend developers use a physical device for testing, for exactly these reasons.
I've been doing some background testing around this, it looks like there is some progress on this but I'm not sure when we will see it working. There is a issue you can track at https://issuetracker.google.com/issues/37129533
In the latest version of the emulator it supports webGL version 2 but not 1. Unfortunately we're only using webGL 1 on Android because of webGL 2 being very buggy on Samsung devices, so we need webGL 1 support. It apparently supports webassembly but I haven't tested this. When running webGL 2 it appears to fail after a few frames. It claims to have no performance caveat, but then chromium prints to the log that it does have a performance caveat and is running using a software renderer. So all in all it's a bit of a mess.