Yes, it is. Republic’s service blends the Voice over Internet Protocol (VoIP) network of Bandwidth.com with the network of one of two cellular partners. VoIP is the technology powering the WiFi portion of Republic’s blended WiFi/cell service. This blending is implemented through and managed by the Republic app. That app is currently Android only.
You are quite correct in that iPhones are capable of WiFi calling over a cellular carrier’s network. They are not, however, capable of blending two separate networks (one VoIP, one cellular). There is no setting for this. It’s accomplished by the Republic app.
Perhaps, but it would require porting the currently Android only Republic app to iOS. Please understand this is much easier said than done and requires cooperation from Apple. Apple would have to make necessary application programming interfaces (APIs) available. To date, this has not happened. It may well happen one day but today is not that day.
I see no reason why Republic would need to do so. The day Republic is able to support iPhones, plenty of folks will want to use one on Republic, no extra incentive required.
The folks running Republic know iPhone support would be a significant market opportunity. The moment technical hurdles can be overcome, I’m quite confident Republic would support iPhones. Smart businesses don’t leave money on the table.