Bahamas phone calling and VPNs

[Woodland Hills]

I haven’t gotten a local SIM card yet so I am calling marinas via my MyIslandWiFi modem with the phone on airplane mode. I also use a VPN to fool Prime and Netflix into thinking that I am still in the US. My question is this: is it going to be any cheaper to call using data through the VPN or directly without fooling the system into thinking I am calling from Miami?
I have a Verizon phone and use their VZW WiFi calling, which I think is their version of Skype. Is this correct? We are on our way to Nassau today to pick up a watermaker part and I’ll get a prepaid SIM card then, but I was wondering about the cheapest way to contact a marina there.
I guess I’m asking if it’s cheaper to call Nassau from Miami or from the Berry’s with roaming charges. And do they actually charge for roaming if you use internet based calling? The phone is in airplane mode.....

 

[Flatswing]

Do u need both? Your Island WiFi mifi device gives you unlimited (& Unthrottled) data for internet including streaming Netflix etc. You are using your VZ smartphone for WiFi calling (which means u remembered to switch that on while you were still on the Verizon network.)
Since the island WiFi is delivered by the same BTC towers (but different frequencies), as cell service in the Bahamas, not sure what the local SIM card offers over WiFi calling.