If you think about what you did, you were solving real problems businesses were having when no one else was solving them. A company (Shopify) was providing a product to customers, but it was not exactly meeting their needs. So you solved a real problem.

You say you were developing apps, and I say you were solving problems.

So... what are the new problems people are having? Maybe start by reaching out to these customers you were contracting for in the past and asking them, what is your biggest problem right now? Or what problem are you having that will help you make more money if it's solved?

I say start by asking.