The Echo was designed to look similar to the Space Shuttle SRB nozzle. However in realife, the SRB nozzle of the Space Shuttle can gimble to make the roll program possible.
*Support the idea here
*Video demonstrating the gimble mechanism here
*Curious about the roll program, watch the video here explained by EverydayAstronaut!
Ps: Another example of a vectorable SRB nozzle was the Delta IV medium SRB. If you notice carefully then everyone will realise the Left nozzle (which is vectorable) and the right one (non-vectorable)
This should be a thing