Palo Alto Firefighters makes them for their sauce.
I know the place that makes them - they have a packetizer. It's a very specialized piece of equipment.
When I start up at my new copacker I'll be able to have some sauces put into gallon bottles - and from there I can ship them to the kitchen to turn into packets.
If using custom labels it gets very pricey, so I'll likely have them packaged generically and then put a sticker on each or something. They don't have the same labeling requirements because they're free samples and NFS.
It's not cheap but it is excellent marketing.