Hi @brigidd and welcome to the Community!
Our Community Manager @southpaw traveled recently in France with a Republic phone. I believe she used Lebara, however, there’s no reason to believe Orange wouldn’t work also.
You are correct. As far as it being less than ideal, it’s the nature of things. All Republic compatible phones capable of using local (in country) cellular service when outside the U.S. are single SIM. A SIM specific to the service one wants to use is required. Switching between multiple services on the same phone requires swapping SIMs.
If you have an older Republic compatible phone, temporarily moving Republic service to that, then using your G5S Plus exclusively with a local SIM is an option but would require carrying two phones.
Presuming a good WiFi or local cellular data connection, yes.
Are they residents of France or are they also traveling there? I ask because if they reside in France (or elsewhere in the EU), you’ll likely prefer to use local cellular service to communicate with them. Republic phones are unable to natively call or send text messages to numbers other than U.S. or Canadian numbers. International calling for use when on WiFi leveraging third party services is added relatively easily at modest expense. Some options are mentioned here: Calling Internationally with a Republic Phone. Unfortunately, there’s no great solution for texting numbers other than U.S. or Canadian numbers from a Republic phone. If the other end of the conversation is also using a smartphone and willing to use the same app, Skype and WhatsApp are options.
If you haven’t seen it, some general guidance for traveling internationally with a Republic phone is here: International Travel with a Republic Phone.