I was once contacted by ledger as well a few years ago, when I wrote some articles in a popular crypto magazine in Brazil. They sent me 2 new devices and gave me some ref codes, but that was it. Never paid me anything.... So I just wrote a review about the devices they sent me, which were pretty good (ledger reputation was much better that time)
I think they prefer to pay this method of sending free devices to youtubers and social media promoters, instead of paying money for signature campaigns.
Not long ago I worked with Satochip for a while and we had similar giveaway with their HW cards for bicointalk community.
I think that exchanges are better suited for signature promotion in forum than hardware wallets.