Thank you for your reply!
Helix works on mobile quite well already, and soon I am planning to make it progressive, that is you can add it to the home screen, it'll work offline, sync with the server when it can, and be essentially indistinguishable from a native app.
I haven't implemented notifications yet because I'm not using them myself, but I'm definitely planning to, apparently many people find them useful.
Yes, I am planning to monetize it, once I'll complete all the main requested features, it'll cost $12/year. But everyone who joins during the beta and sends me feedback will get free lifetime accounts =)