It’s a heat resistant mat for putting your oven on, not a non-stick mat so it’s not super smooth. The pizza would sink into that weave very nicely indeed
There’s a big difference between ‘heat resistance’ and ‘heat proof’.
My pizza oven gloves are ‘heat resistant’ to 932F and I have managed to melt part of them because resistant means they’ll only withstand the direct temp for a limited time.
Edit - and no unfortunately you can’t cut fibreglass. Well you can but you don’t want the end pieces of fibreglass etc in your food so most mats will say Do Not Cut.