I’ve considered using a cell phone mostly as a modem, and then a VoIP service being the “public” number. The VoIP service doesn’t know where you are – you could even route your communications with it to a VPN. The cell provider doesn’t know what you’re doing. You can use all open-source software under your control locally on your device. You can use whatever device or devices you want as a VoIP device, even a laptop, though you can’t get incoming calls unless one device is on. You could use a VoIP client on the phone to mitigate those cases.
I’ve considered using a cell phone mostly as a modem, and then a VoIP service being the “public” number. The VoIP service doesn’t know where you are – you could even route your communications with it to a VPN. The cell provider doesn’t know what you’re doing. You can use all open-source software under your control locally on your device. You can use whatever device or devices you want as a VoIP device, even a laptop, though you can’t get incoming calls unless one device is on. You could use a VoIP client on the phone to mitigate those cases.