While probably a little more involved than installing the Android app, the full Linux version of OOM should work (I don't have a Chromebook so I can't test, but Chrome OS is basically a custom Linux distribution). The other issue you might run into is the Chromebooks being locked to only allow certain tasks if they're school owned (this may also be the case with the Android apps).
Anyways, you'd need to follow the instructions at https://www.techrepublic.com/article/how-to-instal...
and the package that you'd want to install with apt-get would be openorienteering-mapper
Since this involves the command line, chances are this is too involved for what you're doing, but putting it here in case someone else wants to do a one-off sometime.