TLDR; I am bootstrapped solo founder, started my SaaS a couple months ago, ~10 customers are using my product for ~50$/month and today I had a call with a multi-billion dollar company who wants to use my product. I have somewhat of a blue ocean niche product and they expressed their deepest interest in using my SaaS.

As you might have already thought, they require some customization (most of it is on the roadmap anyway) but then also a couple of extra security measurements such as SSO and that the data can't be shared on a database with other customers.

The are very well aware of the fact that I am probably not able to handle this alone and let me know that they know the value of what would need to be done. The also acknowledged that the current pricing plan won't work for them and essentially they are willing to pay $$$$$$

Sounds a bit like a shift to a service company rather than a product company to you? Well, to me it does. I have read the entirety of this great HN thread (https://news.ycombinator.com/item?id=14071025) as well as this https://m.signalvnoise.com/dont-let-anyone-overpay-you/ and I ended up with very mixed feelings:

One the one hand this could potentially skyrocket the reputation of my SaaS, let alone allow me to work full time on my own dream company. There's even another large-sized company that basically couldn't sign up due the exact same security concerns.

On the other, it comes with a seemingly high responsibility, would mean I have to contract some developers, change my sole prop to a limited and in the end they could decide to churn anyway. Moreover, I have by no means the funds to pay for the development upfront. I think that the company is aware of that and it seems like they would sort of support me through it but I have no idea how this would legally work and is just guesswork.

What would you do in my position? Appreciate every piece of advice!