Forth would also be a nice choice.
Give you another example. A watch, not an apple watch, but a simple Casio watch.
One that does time, alarm and a stopwatch. Not connected to anything. What is important here is the battery life, so the less code the better. C would be a fine choice here. All additional code to prevent security breaches would be a complete waste here.
Give another example. As my day-job I develop embedded software for the railways. Current system I work on operates the brakes when the train goes too fast. Not connected to the internet, and no connection would even be allowed.
Written in C. One because it is simple to understand and the developer can focus on getting the functionality correct. Secondly because there is a wide choice of additional tooling and standards that is required to get the application certified.