hmm can you reformulate this part :
"So can I not feature my products in multiple collections but always use the one product URL and remove/redirect the other additional collections URLs I had for that page?
I’m told this would be very difficult and take a huge amount of resources to do. Can you help?"
from what I understand there is a link equity issue as you’ve received 1 backlink to a collection page with a noindex tag right ?
so now you want to know if you can set up your product in several collections, is that right ?