This! What have you got to lose? Worst case, you close down and get an engineering job, which is the same as if you went for aqui-hire - except that you miss the chance to build something great. Don't worry about the big guys, there is always enough space left in various niches. But do take a break first, and find some support somewhere (indiehackers?).
One of the comments has a great point: "You won't get THAT much cash for it, and you might end up at a engineering job that doesn't suit you, with golden handcuffs so you don't leave."