What kind of apps are you making?

Are you making them on iOS/Android?

Who are your customers (audience)?

Can you also make webApps?

How experienced are you as a developer and what are your skills when it comes down to marketing?

Don’t charge $10 for an app, do a free version with ads?

As a solo dev, forget B2C and go for B2B.
There is more money to be made, and it’s easier to cold email/call companies to sell your product.
Also companies usually don’t care about paying a few hundreds bucks per month for your product if you solve a problem. It’s just a small expense on a budget, so they just buy, it’s much easier than B2C!

Honestly, If you can get 10, you can get 1000. How are you marketing?