Native app is waste of money and energy.
Responsive is good enough. Write small app that would only create Desktop Shortcut and icon and assist with registration process. Firts block on web page can be designed to look like native app...
Yes, my general point is that native app is a good thing, but it's only viable at the stage when, say, 10% of the community using the app would make a difference for your strategy. In the beginning, and for the overall site - responsive is the way.
In the very early days of the Apple Store I remember hearing Steve Jobs saying that Native Apps were just a stage we were moving through, and that in 10 years time (ie 2018) the only platform worth coding for would be the WWW. Obviously native apps are alive and well, but with the rapid evolution of Progressive Web Apps, one must wonder for how long this will be the case.
Whatever the case with the potential future of Native Apps, taking the time to grow the community and evolve the platform within the far more flexible platform of progressive web apps is the smart move.