Most first shops die in week one. The owner spent the $500 on the shop, not the customer.
I keep seeing the same pattern.
Someone with a few hundred dollars wants an online shop. They buy a logo, a theme, a domain, sample inventory, and a course. Then they have no money left to put the product in front of a human being.
A shop with zero customers is a website. That's it.
If you have $0–500, the order is inverted:
Pick one product you can explain in a single sentence.
Put a real checkout link behind it. Not a "coming soon" page.
Spend the rest of the money getting that link in front of people who already want the thing.
Instagram and TikTok are enough for this. You do not need ads on day one. You need 20 posts that show the product, the price, and why someone should buy it this week.
If you cannot name the customer, do not spend on branding. If you cannot name the product, do not spend on a store. If you cannot name where the first 10 buyers already hang out, you are not ready to spend at all.
That is the whole game at this budget. Everything else is decoration.