How would you build a half-duplex analog or DVB-T transceiver with this as a basic building block? Yes, possibly a single digital input pin.
How would you select between two LO frequencies for a repeater offset or for a satellite up/downlink selection, etc.? Yes, a separate digital input pin.
Don’t tie these two together and it gives you more options.
Eg., this could be the basis for a LoRa terrestrial radio on 1.2, 3.3 and 5.9 GHz using the SX1280 chip, which you already know how to use (or buy on E-bay). Now the frequency offset is not a duplex offset selector tied with the TX/RX line, but maybe an in-band frequency select.