The question to me is how will outsourcing support you going to market with your idea? Fyi, I assume from your tone you have the seed funding you need to build the product available to you, yes? Or are you saying that you are going to seek funding for the outsourced product dev? I think the idea that you are going to get seed funding for building out the MVP is highly speculative. But even if you were able to thread this tiny needle, then you will likely get awful terms. All that aside...
The operative question is can an outsourced product development setup support you actually going to market? A few things to think about from my POV:
An MVP is likely not going to generate much revenue, if any, but will get you users/signups that you cannot monetize who you will learn from so you can build a useful product. So that is not the gate you need to get through to actually raise A round money.
Good tech startups are constantly iterating in the following way. Engage market, learn, enhance/revise product & strategy, repeat. They do code drops daily sometimes, and are constantly tinkering and adding features, changing existing features, UI etc. Ask yourself, how can you do this efficiently with an outsourced dev firm? Example: I just did a con call with my engineer and product guy on a startup I'm fractional CRO for yesterday, reviewing the three features we need for the week of the 11th to do demos for 3 new customers we are chasing. In the early phase of a tech startup this is to be expected and welcomed.
With an outsourced dev partner there are two elements of friction that you are up against as you want to iterate on product. The first is change management. Since they are not really part of the team, all changes need to be documented and agreed to and then the acceptance of them has to be formal. And of course, every iteration costs more in fees so every change you want incurs more cost and time than it would with an inhouse dev. In the example I cite above? We have no out of pocket cost to do that three changes we need to go win those three customers (worth 60k ARR to us, fyi).
Alignment of incentives. No matter what, the incentives of an outsourced engineering firm are to generate fees from you. While many will be very balanced about this, as they know what they can't just soak you, there will always be this tension.
Pride of ownership. I think that engineers who have equity and are part of the founding team have a tremendous amount of pride and forgive me for saying it this way, but also their egos invested in the product they produce. They have also put all their "chips" on the company if they are doing it full time or close to it (many will consult on the side to pay the bills in the early days). This shared fate drives commitment and very different behaviors than you will get from an outsourced firm.
"Rock star developers" Chicke throws this term around in her commentary and it makes me laugh. The fact is most tech startups are not doing anything that fancy or groundbreaking technologically. Sure, if you hire some kid out of school who's never built an actual working product before, it will look like heroics. But instead, if you find some dev/engineer who has built actual working product/systems before, who's tired of being an employee and wants to take their shot, you aren't looking for "rock star" qualities. Just good solid development EXPERIENCE - you know, an ability meet deadlines, get product into production and work with others. This to me is much more valuable than "rock star" status. You aren't painting the Monolisa, you are just writing some software that is likely no different wrt to the underlying functionality/technology from a lot of other systems that have been built before. Good design is a must have of course, and good UX, but you already have those skills.
So, in conclusion what am I saying? Outsourcing is a real challenge. I consulted to a startup last year that had to put their entire go to market on hold because what they learned from their MVP meant they had to build an entirely new product (mobile app and back end) from scratch and didn't have the funding to do so, and couldn't raise either.
Last. Do you want some advice? Focus on finding a dev/engineer who believes in what you are doing and wants to do a startup. Co-found with him/her. Your idea isn't as valuable as you think, and will likely change a lot once you begin to try and get it used anyway. Also, stop all the "business planning" - it's next to useless at this point in your development. Yes, do strategy (market research and competitive analysis) but operational plans etc? Irrelevant and a waste of your energies.