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Nobody can give you an answer. This is the "how long is a piece of string?" of modding. The time required is entirely contingent on the specifics of what you want to do, your relevant skills/proficiencies, and how much free time you have to devote to it. Maybe you could do it in a week, maybe you'd still be working on it in a decade. If you want collaboration then there is no reason not to lay out what it is you have in mind. Then people might actually be able to give you some informed opinion on how feasible what you want to do is, and what sort of effort would be required. But right off the bat, the fact that you think it requires a team means the likelihood of it ever seeing the light of day is low.

You're better off simply doing it and then announcing it.