Is dynamic localization a valid and elegant solution or is it just an ugly hack? I want to use it but I also want to keep my code as flawless as possible (even if I'm still learning, I'd like to write high quality code).
It depends on your application.
If your application is fine with returning failed allocations and can handle the case, then it's okay. But if you have a real-time or safety critical system, for example, something running on a vehicle, robot, or flying device, you usually can't risk failed allocations. In that case the better bet is to reserve memory on the heap for your array and ensure that you are within bounds or within a certain threshold by checking on push data to your array or using a circular buffer.
There are many approaches to solving a problem, and many ways to implement the solution, but the path you take usually depends on your application and your constraints. Think about which set of tradeoffs with respect to performance, safety, and memory usage makes the most sense for what you are trying to do.