Is an online store passive income?

No. It is a business with unusually flexible hours, which is a different and better thing to expect.

What decides it

The work never stops entirely, it changes shape — from finding products, to buying traffic, to service and stock. What can become close to passive is the revenue from customers who already buy from you regularly, and that is the argument for building that base early.

The part that gets skipped

The number that decides whether a store works is not revenue, it is what is left after the cost of the goods and the cost of getting the customer. Plenty of stores with impressive revenue make nothing.

Repeat customers are the whole game. Winning a customer costs money; selling to them again costs almost nothing.

Most of the money in ecommerce is made in unglamorous categories bought regularly, not in the ones that photograph well.

Where an app fits

This is where an app earns its place — it exists to make the second and third purchase easier, which is where the profit is.