MOSI/MISO is the SPI equivalent of Tx/Rx for UART (except the lines are not crossed: MOSI connects to MOSI, and MISO to MISO). The other difference is that's it's a bus, like I2C, with one master and one or more slaves. So you can connect a screen and a LoRa chip, for instance. However, you need a separate SS (Slave Select) line per device. You're going to have difficulties finding enough pins for this. As suggested, it'd be much better to use a managed chip (MCU + LoRa chip). I've tried a few things but it's too cumbersome. I switched back to M5Stack for this.