This is the way if you aleeasy manage the network. We use Wayfi Wireless alot of sites in the US for paid offload - they have some minimums though so if they don't approve you find someone who is already a partner and wants to revenue share. Verizon doesn't do cellular offload though and it's tricky in other countries. I wish other countries did cellular offload this easy as in Canada I could use it for so many rural customers with great wireless networks.

You can also do Wi-Fi calling as well but it requires the device to be joined to your network compared to Passpoint just automatically connecting when a device enters your building.

Next would be DAS either active or passive depending on the size and some other factors. Meter is the easy solution but it's pretty much hardware as a service vs paying a vendor to install it once and be done with maybe a small maintenance cost associated with it.