Inside of the Meraki platform, I don't believe there is a way to do this yet. I use Layer 7 to block certain countries and there isn't even a way for me to make an exception to that if I want to whitelist a few URLs. So as @PhilipDAth pointed out, your solution will likely be outside of the Meraki platform.
Adam R MS | CISSP, CISM, VCP, MCITP, CCNP, ITILv3, CMNO
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