Yes, it would definitely be an uphill battle. But I wonder if you could build a platform where a progressive web app felt enough like a mobile app and therefore enticed more app developers than requiring them to learn native tools for another platform
Can a new phone platform be successful if it launches without whatsapp / wechat / line / instagram / [add a dozen social networks there]?
A phone that doesn't let you speak to your friends, family, and coworkers is going to be a tough sell. Getting all those from the get go, without a large user base to motivate the developers, is going to be a tough sell.