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.
If your drone runs something like px4 or ArduPilot, then you would basically only have to implement mavlink (https://mavlink.io/en/) in Nim and you could read data from your drone and send commands to it.
Mavlink is pretty straightforward. 2 years ago I made a minimal implementation for Matlab and Simulink (for this thing https://www.youtube.com/watch?v=aGkW149IvqI). Which was horrible(ish), but doing it in Nim should be pretty easy. Nice introduction to binary protocols / file formats and XML.
On the hardware side you'd typically either use an RFD900 radio modem (long range, low bandrate, high latency) or wifi modules (like esp32s, low range but faster) on either side that as wireless bridges. One hooked to to your PC with USB, the other one speaking UART to your autopilot (something like a CubePilot or cuav x7+).
It would be easier reusing already made libraries in eg. Python, like pymavlink and dronekit (basically a higher level abstraction over pymavlink), but it's entirely possible to do it from scratch from nim in a reasonable timeframe, if you're up for it, I think.
I don't check the forum that often these days but ping me on discord if you have questions.