My side project Nucleus Digest https://digest.meetnucleus.com index of great startup content. I market it by publishing content on twitter, point resources to HN, Reddit, GH community questions etc.
1. You should work on acquiring customers / beta signups while building MVP, it should be parallel not serial.
2. Have you done any validations that it's a important problem for your customers i.e. vitamins vs painkiller
3. You shouldn't be worried about a YC competitor. Focus on building, talking to customers and growth.
A good senior developer is proficient in more than one languages, knows or figures out quickly the pros and cons of any technology. They have both depth knowledge in certain part of the development stack and breadth overall.
Assessing seniority by just number of years of experience, or knowing a hot technology doesn't make one a senior developer. A solid Aptitude + Attitude towards software development will make you a stronger developer, and that will also help you pick up any new tools, needed to get the job done!
Sometimes it's better to invest in yourself, if your current role is helping your grow. You want to make sure, you're not only enjoying your current role but you'll be more marketable as well if you continue.
