I don't know what market your app is targeting or what sector your app resides in. I point that out because the reality is that you should develop on whatever platform your target market uses the most, with an eye to understanding where those users are heading in the future.
Case in point, in the video gaming world, device usage differs between not only type of game but also demographics of of the user base and in some cases where they live. So an action game targeting males living in the US, ags 12-28 who are frequent gamers may use a different device as their primary platform versus a casual game targeting age 44+ females who live in AsiaPac versus...
Know your market, the how and what of use, and develop accordingly. There are exceptions where the product and market intersect but your chance of success will be higher if you start with the user versus the product. I've seen both and the "build a product figure out the market later" scenario, at least in my experience, has not worked..ever.
So before anyone objects...yes, there are exceptions despite the odds..but do you want to live by exception (high risk) or reasonable best effort (lower risk)?