CDMA will not work in Europe as Europe only uses GSM.
Unlocked iPhone 7 are not currently available for sale in the US. But there is an alternative.
You can purchase a Verizon phone from the Apple store and pay full price. Even though Verizon is CDMA, the SIM slot is unlocked and with the proper sim for your provider in Europe will work on the GSM networks. You may have to pay for a month of service on a Verizon prepaid plan just to get the phone. Do not get a subsidized phone.
Do not consider Sprint as the sim slot is locked. Same with T-Mobile and AT&T and you would have to beg them to unlock the sim slot. Only Verizon has the sim slot unlocked.
You also need to know that you will have no warranty in Europe. Apple's warranties are not international and are only applicable in the country in which the device was purchased.
I know that Verizon phones will work in Europe based on experience. I take my Verizon phone to Europe on my trips and get a sim when I arrive. I have voice, text and data without any issues.