Although there is not a picture of delivery, there are GPS co-ordinates,
Have you checked those?
The seller won't be able to make a claim because the items are shown as delivered and if you open a case for 'items not received' then the seller would most likely win it.
You can try a claim with Paypal but, again, as the items are shown as delivered, they may refuse a refund.
So, check the co-ordinates and maybe contact Royal Mail to see if there is evidence of mis-delivery.
You can't open a case with Ebay and Paypal at the same time although you can open a Paypal claim if your case with Ebay fails.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)