If not, try removing one, then visit an auto parts store and use it to compare to their stock. You may find something of similar size. Places like Autozone and advance Auto normally have stands with bunches of them in containers.
YES!! I found both sizes needed for my 2015 & 2016 Muranos.
The smaller ones are used on the left & right side-splash panels that cover the engine oil filter etc., plus a few places under the engine. They are: UPC: 715668952430 (ebay # 223716471521) which I bought on ebay in a pack of 50 for $5.94 with free shipping! WAY cheaper than a hardware store or Nissan dealer!
The larger ones are used under the engine & CVT areas behind the bumper: 9mm shank diameter x about 5/8" shank length below the collar (not counting the center pin). DORMAN 961-033D which I bought at a local Advance Auto Parts store. Only 2 per pack for $3.99, but still less than you will pay at a Nissan dealer parts dept.