USPS might have lost package - best path forward?

Hi all - so I've got a small Etsy shop, where I've had ~60 orders over the past year or so. My items fit in a 10x7x3 box, so I've always just had that shipped from my own residence mailbox. That's always worked fine, until recently.

On 11/26, I placed an order in my mailbox. I've got doorbell camera footage of the USPS truck picking up the box that evening. Fast forward to 12/2, and the USPS tracking number is still showing as 'pre-transit' and 'USPS is awaiting the item.' My fear is that the box got lost in the USPS truck or somewhere in USPS's handling.

When I sent a help ticket to USPS explaining the above, they simply stated that they have not received the item yet, and closed the ticket. The next step I can try and take with USPS is a "missing mail search," but USPS won't let me initiate that until tomorrow (12/3) - as it has to be at least 7 days from the shipment date.

In talking with Etsy support, this item should be covered under Etsy seller purchase protection - if the buyer creates a case with Etsy. They also state that with a 11/24 order timing, the buyer became eligible to file an Etsy case as of yesterday (12/1).

I'm curious to hear from other Etsy sellers. What would you do in this situation? Would you first try the USPS missing mail search, and go from there? Or would you just pro-actively reach out to the buyer and give them the instructions for submitting a case with Etsy? I suppose there is a chance that the box gets found within USPS's handling and eventually delivered, so I've just been hesitating on how to best proceed.

Edit: for pricing info, the item purchased was $63.96, after tax and shipping.