I was involved with a SaaS product that launched a landing page and made clear that the product was still in development, but that we would give earliest access to people who pre-paid for the product. We also allowed people to choose what they paid, and promised them that payment would stay in-effect for several months.

We generated revenue the first day of posting the landing-page publicly and increased revenue month-over-month. However, we discontinued the product as it was simply not big enough of a market for us to justify continued time and energy.

But I would encourage you to pursue a similar model in that it's a great way to test and validate the pain others experience for the problem and a great way to ensure you're building the product to satisfy real customers.

Happy to talk this through in more detail in a call