Of course we can't use official club logos on merchandise that Kenny creates - but we can do pretty much anything else we like
The thinking is that the fans themselves know what would work for their club. Kenny is a Hibee (don't hold that against him) so he knows what works well with Hibs but that won't necessarily be right for other clubs.
Every club has their own songs and their own history so it's up to you guys to come up with design ideas for Kenny to turn into reality.
See Hearts, Hibs and Alloa for some ideas of other designs that already exist to get an idea of what this man can do