Isn’t the question “what camera should I take in addition to the Insta360?”
Thats the starting point. Size wise FX2/3/30 might be worth looking at?
I suppose it all depends, too, on the intended audience - family & friends, film festival submission, BBC documentary etc. I think if I was undertaking such a mammoth project I’d want a decent cloud account to offload files as I go. The Blackmagic offering might be worth investigating?
Sounds fun. And hard work!