If you want a buss into a buss you have to take the first buss by an physical output then re inject it into an physical input and select the source in your second bus 😉
So I am afraid there is no intention of adding routing from a group to a group or LR/aux to LR/aux in the core as it would cause issues unless you were very careful with what you were doing and made allowances for added latency.
The workaround for this as @Hugo mentions is to either use an analogue or digital loopback, which will achieve this at the cost of latency/coherency.