I believe the $10 is for "international roaming". If you put the phone into Airplane Mode and then turn on WiFi, you should be getting it over WiFi instead of the local phone service. Verizon won't know where you are, just "off line" from the cell network.
Of course you'll have to have WiFi service from something like a mobile hotspot. That's what I did the last time I traveled internationally. You will have to activate any WiFi calling features on the phone.
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