I'll say this bluntly : this is too big of a project for someone who hasn't done any low-level software already.
Nim aside, start small and simple, define clearly what you want to accomplish then iterate. Learn how things works then you can decide which tools is the best to use. Generally speaking, manufacturer who produce programmable drone will provide a C or C++ SDK to interact with it. Your course of action will be to understand said SDK and write (or generate using c2nim or @PMunch <https://github.com/PMunch/futhark/>) bindings of it from Nim. You will have to understand the C/C++ compilation option and properly pass them to Nim. If you want to train interacting with HW from SW in NIm, try with a microcontroller first. Last I checked, @Elcritch had done wonderful work with <https://github.com/EmbeddedNim/nesper> for ESP32 for instance. Pop by in the embedded channels and ask your question.
