Is it possible for a skilled development team to develop a metaverse implementation, using Unreal Engine? Yes.
Is it possible for a skilled development team to develop a crypto-currency based purchasing system for a game/application built on top of Unreal Engine? Yes.
Is it strictly required to have a downloadable installer for running something developed on Unreal Engine? If you want to use VR goggles, then, yes, but if you want to use keyboard/screen, and are OK paying for the resources used, then pixel streaming could do it using cloud rendering, too.
Does anything like that exist, work, and have public access today? No. Apparently, the people who attempted to build such a thing, were more interested in selling NFTs, than they were able to actually develop a metaverse application.