There are some opensource LTE UE stacks, for example srsRAN has one. Legalities aside, it can in theory connect to a public network using an USB sim card reader

There are some opensource LTE UE stacks, for example srsRAN has one. Legalities aside, it can in theory connect to a public network using an USB sim card reader (or a software sim emulator if you know the required keys). For a stationary node you should get more or less the same performance as good LTE dongle, but dynamic applications will perform very bad. Unlike WiFi, LTE allows quite high latencies, so the host computer can do all computations, no real need for FPGA code. For WiFi you have OpenWiFi: https://github.com/open-sdr/openwifi https://github.com/open-sdr/openwifi It currently has 11ac support and WiFi6E is in development. Operation on 2.4GHz can be a bit confusing due to lack of 11b support but on 5 or 6GHz it 'just works' (though note lack of DFS support).