Gyros are typically allowed, although only on the rudder/steering control.

From Scale Masters rule book

14. A gyro may be used on rudder control only.

From the Top Gun rule book

A. Rate gyros are allowed to aid in rudder and steering control only. Rate gyros are NOT
allowed to aid the control of ANY other surface or function.

Not sure about the NATS but I would be surprised if they were not allowed in Scale.