The advantage is social, stating "I've supported this art, this stick generates the QR code that proves that"
"Merch Alternative" I mean like instead of DRM Blu-rays or DVDs etc.
The device being airgapped so that the only input is power, should socially suggest that one can't be tampered with or forged (i.e. by extracting a signing key).
This solves the problem that many aren't reminded of the importance of supporting artists that create the art that they use. It adds an element to the conversation that helps individuals find an excuse to remind each other to pay monetary tribute to source artists (including film makers, animators, audio book authors, etc).
As a dual function, the signing key could serve as a cryptocurrency wallet. So simultaneously while checking the authenticity of one friend's contribution, the friend that's doing the checking can also make a contribution so as not to appear hypocritical.