Should I apply for masters degree or continue building things?

Build things; that's how you figure out what the interesting research problems are in some small niche of the world.

With no industry experience, you'll not get a high-impact thesis. By building things you discover all sorts of problems deep in the guts of industry that are worthy of serious academic research.

If you're lucky, you'll have a half-built academic-content project before you apply for a thesis-based MSc, and you'll be done with the MSc in a year.

This approach works with Phd as well - except that it takes longer than a year due to Phd having the expectation of larger scope and impact.