Validation and monetization - two great questions.
See some great tips on how to do validation in this answer: https://clarity.fm/questions/6423/how-do-you-do-market-research (happy to help you plan your specific validation process)
Regarding monetization - the most suitable business models in this case would be commission / intermediate fee taken from either the advertisers or the owners of the advertising spaces (spas, coworking spaces) or both of them.
Good luck
I've successfully helped over 350 entrepreneurs, startups and businesses, and I would be happy to help you. After scheduling a call, please send me some background information so that I can prepare in advance - thus giving you maximum value for your money. Take a look at the great reviews I’ve received: https://clarity.fm/assafben-david