I don’t think it can be said to be an alternative to Newegg. Newegg is an official merchandise seller, and if you get borked by an official store page, there is support to help you. Jawa.gg is mor like Ebay, with a focus on gaming related hardware and gear.
Newegg and Amazon are now marketplaces, too, and often redirect the “customer support” you would otherwise expect onto the retailer/individual selling on the marketplace. You do at least sometimes have the preferred option of purchasing directly from Newegg or Amazon, in which case there is some large, responsible entity to deal with rather than a 3rd party and possibly small / shell / vapor retailer. Newegg has had its share of official customer support complaints, FWIW.
Anyway, I haven’t used jawa myself, but I agree Ebay is probably the best analogy. You’re ultimately dealing with individuals, not a corporation, so trust should be apportioned accordingly.
So sussing out information on the sellers’ reputation is a big part of it. It looks like there is also a 2 day period to dispute the item for buyers. So I may give this a shot in the future. Maybe at the end of this year for Black Friday or Christmas.