is there actually a way to cancel and not accept the credits? Most carriers just give them to you when you cancel.

have never needed to use card insurance to recover full cost of tickets - have used them to cover change fees, etc. due to illness and being not advised to fly. And not sure if Amex is different here, but my understanding is Chase at least will cover the full cost of tickets if you don’t end up using the credits. Ie, if you cancel for a covered reason, you can claim the cancelation fee (if applicable) if there is one, then a year after issue, if you haven’t used the leftover, you can claim that cost as well in a follow up claim.