Radius based VLAN assignment with Ubiquiti

Hello,

I was just wondering about some pros/cons in regards to a future project, we are tasked to implement a radius based wireless (for dynamic vlan assignment) in multiple buildings that lease out office space to customers (it's a shared building with a shared network, nothing fancy, just vlans and an ASA)

There are 5 sites in total and we are heading towards an azure based machine running server 2016+NPS (which is already setup due to a number of other services that we have on azure like the ubiquiti controller). I've been looking into running a vpn between our sites but since we took this over from a previous MSP, IP addresses/scheme is practically the same across all sites. Since we've implemented a new wireless setup, I made the subnets unique at each site incase when we deployed it to not run into any issues with site to site vpns between the sites if we were to ever implement that solution.

I've labbed this up and managed to get it working all fine although was asked to test it without a VPN to azure. I've been looking into the same solution and the cons with doing this over the public internet with no vpn vs a vpn and even explained the issues we would solve (and run into) but feel like I might not be catching all the cons/pros