No it wouldn't work. I see HyperMD is based on Code Mirror and as of now that editor doesn't support mobile.
Code editing on mobile is surprisingly under-developed - most libs were created a long time ago, before mobile was so widespread so none of the major ones work on it.
The most promising effort for mobile is Code Mirror 6 but last time I checked it was still a long way off. If they ever release it, maybe HyperMD will upgrade to it ("maybe" because it would be a tricky upgrade due to the API changes and the fact the existing plugins won't work anymore).