there are post which discuss the problems of connecting a SX1278 to a UNO or Nano , e.g. see sx1278-on-nano-tx-and-nano-rx
the classic Nano uses 5V logic the SX1278 3.3V it is not a good idea to directly connect the devices - use a level shifter
you could save yourself trouble by moving to a board which incorporates a microcontroller and a LoRa module, e.g. ttgo-lora32 , Adafruit Feather 32u4 LoRa, TTGO-Beam, Hiltec LoRa 32, The Things UNO, Adafruit RP2040 with RFM95, etc
this saves the problems of level shifters, jumper wires which give poor connections and intermittent faults, etc, e.g. see river level monitoring
make sure your LoRa module uses the correct frequency - see LoRa frequencies-by-country