I would be surprised if a hitch ever becomes available from Lexus USA. They usually supply hitches at the time a vehicle is introduced as they did with the UX in the U.K. and the NX and RX in the U.S. Maybe an aftermarket hitch will eventually become available but the UX is selling in pretty low numbers ... only a little over 16,000 in 2019 - might not be cost effective for an aftermarket hitch company for such a low volume vehicle. I don't like carrying bikes on a roof either but I've sometimes done it. I carried bikes on the room of a Mercedes for 11 years since a receiver hitch wasn't available and I wasn't about to trash the trunk lid with a trunk lid mount bike rack.
I now check on hitch availability before I buy a vehicle. I even installed a 1 1/4 inch receiver hitch on my wife's Prius so she could plug in a 2-bike rack. I'm planning to buy a 2-seat sports car next summer for which neither a roof rack or receiver hitch is available. Although I'll buy the car even if I can't carry bikes on it, I'm already investigating having a class I 1 1/4 inch receiver hitch fabricated for it.