I don't know if you can separate "nature vs nurture."
Almost certainly they work together hand in hand as you say, and I suspect no one in their right mind who thinks "nature" is an influence would deny nurture also is at work. But the reverse is not true. Those who push "nurture" are heavily invested in a total "blank slate" and I think we are seeing that as we observe the surprising lack of research on instinct the results of that attitude.
There is no way in 2021 we should be lacking a conclusion on beaver-dam-building or many other aspects of animal behavior.