You don't need a patent lawyer, just read 35 U.S. Code § 271. " . . . whoever without authority makes, uses, offers to sell, or sells any patented invention, within the United States or imports into the United States any patented invention during the term of the the patent therefor, infringes the patents.
Amazon, Walmart, etc. aren't likely the ultimate targets of the suit. The suits are designed to bring in the producers under the indemnity portion of their contract with the retailer. Its a jurisdictional hook and way to effectively multiply the amount of pressure on the actual infringer, by threatening to cut off their access to the retailer (which could be accomplished in the ITC) and leverage possible contractual damages they face from the retailer. The ultimate goal is to pressure Everlight, Eaton, and whoever else is making the light bulbs to pay for a license, and using Amazon and Walmart to force them to do so.