Wearing multiple hats is for the partners/owners. Startups don't hire generalist to do anything. I worked at Zomato's NEXTABLE (reservation software on the iPad) as the iOS dev along with two interns. I used to do some Nodejs and messed around in Java in addition to having done marketing and financial modeling as a real estate developer. Still - I was hired to work on the app, not server-side, not marketing nor making phone calls.
Pick something you like and get awesome at it and iterate from there.
Pick something you like and get awesome at it and iterate from there.