If the H5P activities don't need assessment, you can display them in the Moodle Mobile app by hosting them on a Wordpress site. The embedded item in your Moodle site will show perfectly in the Mobile app.
We use a dedicated Wordpress site with the H5P plugin to make all our content (if it needs assessment then we simply export it and upload it to the Moodle H5P plugin) and find this a much simpler solution.
Hope that helps.
As I said: We'd love to contribute the required code ourselves, but right now we're focussing our resources on some other aspects of H5P. However, we invite the moodle community to have a look at the source code (it's all on github) and make the changes that are necessary.
Thanks for the work around solution, Dan. I still need to explore the H5P assessment as it doesn't have the item analysis for the Quiz module.