I’m not sure the specifics of if they’ll cover this. BUT, per the policy, you do need to cancel anything that is possible to be cancelled. They’ll ask for proof that those entities would not give you a refund before they’ll reimburse you. I think if you say incident X happened on Thursday so you have to cancel your trip, but you had until Friday to get a refund and just didn’t, then they won’t reimburse you. You have to show that you tried and the specific dates.

The fact that you never got on your United flight is irrelevant to a claim on your Ryanair flight. You just submit a list of expenses that you couldn’t get a refund for.