I solo founded a business and it just crossed 100K MRR (still solo). The trick is:

1. Don't give up after the first month of no traction, if you can get at least 1 customer at this stage that is a good sign.

2. Make contact with every customer you acquire, find out why they installed your product and what they want from it. Build any feature that they say is missing and offer the best customer support possible

3. Repeat this for a period of time. Once you have more customers the circumstances will change but this how you go from 0 -> 1 and get some runway IMO