Could a phone establish data connections and load webpages independent of either WiFi or a SIM card? Volk Fi apparently thinks so. This company is currently advertising its first smartphone, the Volk One, which can apparently form part of its own 'mesh network' with every other unit of the same around it.
https://www.notebookcheck.net/A-phone-that-gets-free-internet-This-is-what-the-Volk-One-offers-apparently.414868.0.html