Crystal for LoRa Transceiver
If you use a TXCO, you only need to worry about the output swing (max 1.8V peak-to-peak) and frequency stability.  The load and shunt capacitance and ESR are only relevant for a crystal.  With a TXCO, you will take a single ended output of the oscillator and drive XTA, XTB remains unconnected.

Frequency is set by the Frf register which is in Fosc/2^19 units allowing for the use of a range of crystals/oscillators.  If you are using prebuilt libraries, some of them assume a 32Mhz crystal.