"This research was carried out as part of the project «Digital Thessaloniki 2030: Promotion of the digital profle of Metropolitan Thessaloniki through blockchain and digital tourist card-: #Thessaloniki_Tourism_Blockchain» (Project codeΚΜΡ6-0077937) under the framework of the Action «Investment Plans of Innovation» of the Operational Program «Central Macedonia 2014 2020», that is co-funded by the European Regional Development Fund and Greece