Starting a new business is hard enough as it is - please do not complicated it by adding in something that brings limited tangible benefits to the company, whilst making it unnecessarily harder than what it will be anyway.
Either get fluent now, and then start your business - or start your business with Windows and move on when you’re profitable and can afford the reduction in productively while you learn the ropes.
Do not go anywhere near MacOS - you can’t afford it.