Meta IIRC is one of several outfits which unsurprisingly discovered that (as a corporation) the cure is just purchasing policy. When your new Doodad vendor sells you a product that is IPv4 only instead of saying "Oh, shame, OK, set all corporate systems to IPv4-only" you point them to the line in your purchase contract which says you require IPv6 and it's not your problem it's their problem, do they want to fix it or refund you ?