This idea is very nice! Food always brings people together so showing gratitude with "gratitude packages" filled with food is very interesting. Maybe you can implement a process that would allow everyone to create a package with a note without having them to actually buy the items (it can be an economic barrier for some workers). Like having a snack corner with available food and people could take the snacks and then create the package with a note. The expression of gratitude is quite strong since the person takes take to make the package and write the note. Thank you for sharing your idea!
This idea is really interesting! I would love to see the implementation, but I would be careful on selecting people with various backgrounds and personalities, not only the one that are naturally at ease with others. If there are various ambassadors or if there is a system that allows a new ambassador for a precise period, that would foster gratitude even more. Because with different personalities, ambassadors will be able to discuss with everyone within the organization and find way to help everyone to express their gratitude. Thank you for sharing this great idea, hope the best for the next.