These merchants were added to the game in Patch 18.104.22.16875 on May 10th, 2016. They sell all the items that used to be sold in the Phirius Shop portion of the Item Shop, plus a little more.
His initial dialogue is broken into 6 sales categories. All Phirius Merchants sell the same items.
When you purchase an item from one of these merchants, it goes in your regular inventory even though it is an Item Shop Item and can be moved to your Item Shop Backpack.
Pages in category "Phirius (Merchant Type)"
The following 7 pages are in this category, out of 7 total.