Update 3/6/23: It appears transferring is now working.
You can now exchange points between Radisson Rewards America and Choice Privileges at a 2:1 exchange rate. Two Radisson Rewards Americas points can be transferred to become one Choice Privileges point, and one Choice Privileges point can be transferred to become two Radisson Rewards Americas points.
This can also be an option for Citi ThankYou Premier cardholders to redeem each ThankYou point to ultimately become 4 Radisson Rewards Americas points.
Hat tip to bestbet33 and jaycis