How to proceed with this return

Buyer messaged item doesn't fit. They had not read the title properly nor seen the pictures which had sizing label. I pointed them to these details and also that I have clearly listed a no return policy unless it's my error.

They initiated return - "Doesn't fit".

As goodwill, I offered almost half the purchase price back and to keep the item to donate or sell.

If they return the item, they would be out initial shipping fees and return shipping fees so it works out in their favor to keep however they didn't respond to messages nor accept offer.

My second time experiencing a return request in a decade. I don't sell much.

Upon searching, I see that Ebay indicates a seller can still accept the return request which I would like to do, to just get this over with (fingers crossed they return item in original new condition) but see no way to do that as the status for this is stuck at "pending offer acceptance from buyer".

I looked up Q and A and it seems buyer is given 21 days to accept offer? Wow!

At that point if they decline offer, I don't want Ebay to automatically refund them the entire amount and allow them to keep the item.

Ebay won't answer calls nor could I find a way to chat with an agent. Just curious what I can do to resolve this.