How do you prioritize features and plan product development?

One of the biggest problems! I have talked to many startups and some have mentioned Aha! for this. Key is to make business & product think better about business impact.

Well, in my opinion, it depends on what stage the product is currently in right now. In general Kano model helps to constantly evaluate the feature and sub-features. For me the mental mapping is: Kano model + Technical Debt + Time needed to validate the value proposition of the product. The rest is just Jira's epic roadmap timeline.