I have just gone through a similar conquest you are about to embark on. We just launched our app in Oct with 10k users now and gearing up for a seed round.

Watch the Y Combinator video libraries.

The video on: Tempting startup ideas you should avoid, this one definitely hit home for us.

You could definitely raise a 500k pre seed with what you have regarding your surveys and pre registrations.

Probably a good idea to make sure you are solving a real problem, so get out and try and figure out if this problem you solve is that excruciatingly painful for people they will actually use your product.

Go for it 🔥 Good luck

200k from one customer is amazing, there must be a lot of merit in your product If someone is willing to pay this. Sorry to state the obvious, is there more customers you could find like this?

Have you considered a startup accelerator program?