Call me old-fashioned, but I wouldn't protect a "delicate" groundsheet of some really expensive UL tent - a significant investment that should last years - just with some window film that has no known published mechanical properties, especially going anywhere Alpine.

Tyvek has published mechanical properties. We know exactly what it is, non-woven HDPE. We know tensile strength, elongation, etc.

"Polycro" means exactly nothing, nada. We don't even know what it is made of (well, "polyolefin", but see below). It's just an empty marketing buzzword just to sell window film more dearly. No published mechanical properties for either GG or other ones at all.

Polyolefin is just a generic name for any polymer made of olefins. That could be all sorts of polyethylenes (HDPE,LDPE,...), polypropylenes, just about anything. All with wildly different properties.