Turn indicators also show R1 turns. Some can even show higher rates.
Not really correct to say a TC shows *AoB* for a rate 1 turn. It shows that the a/c is *doing* a R1 turn but not how that rate of heading change is achieved. If balanced then the AoB must be that needed to achieve R1 - but the TC isn't showing AoB directly. You have to derive that information yourself. If not balanced the a/c could still be doing a R1 turn - but it won't be at the AoB used for a balanced R1 turn.
As an experiment, next time you fly set what would normally be a balanced R1 AoB but use rudder to prevent any heading change. Watch what happens to the TC.
A disadvantage to a TC is during inverted spins. AoB and turn direction don't match so the TC can give erroneous turn information, unlike a 'standard' Turn Indicator.