There are literally thousands of these 'sources' for every NOC on a targeted mission. Many of these sources aren't even paid, they're just predisposed to be friendly to the nation who wants the info and willing to pass along things they see or hear in exchange for a favor or access. Most of what they pass along is irrelevant and useless impressions or chatter but it's all captured and cross-referenced by analysts.
When Jensen makes a two day visit to some Asian country like Singapore, he probably has over a dozen meetings including various local employees, distributors, vendors, govt agencies or media contacts. Nvidia's posture and distribution plans in Asia are of great interest to China, since they're trying to divert a good chunk of those GPUs to China. I have no doubt the Chinese (and other intel agencies) got reports from over half a dozen different sources regarding what happened during Jensen's visit.
Jensen is very smart and has a lot of experience. He knows he's a high-value target and everyone is info gathering on him. Hypothetically, even if he was banging the hot, young distributor rep when visiting Singapore (and I doubt he is), she wouldn't get any actionable intel. Not because she might send an email report to Chinese intelligence but because she'll certainly give a detailed report to her bosses at the distributor. All of NVidia's distributors are trying to glean any competitive insight or favor from NVidia they can.