All income is reportable, no matter how small the amount.
The $600 rule only applies to the person/company paying you. They must issue a form 1099 if they pay you more than $600. The IRS considers anything on a form 1099-NEC to be self employment income.
How you report the income (what type of income) depends on the details of your activity, whether it is "other" (unearned) income or self employment (earned) income. For guidance, see https://www.irs.gov/newsroom/hobby-or-business-irs-offers-tips-to-decide
I agree with Mike9241, it sounds like you have self employment.
