It’s possible for a certain hardware/software setup not to support a certain codec. For example, my jellyfin client (Finamp) uses the iOS native decoders (afaik), which means opus files are practically broken. My music library (8000+ songs) contained exactly 1 lossy file, which just so happened to be an opus file. I decided to spend the extra ~20MB to standardise my entire library to flac files, ensuring I could play every song on all my devices.
Edit cause I posted too soon: you are generally correct; only in very specific circumstances will you encounter compatibility issues like this one in the modern world. This is 100% apple being apple, and you can expect pretty much every other (reasonably modern) device to support all codecs you might encounter in the wild.
I’ve had good experiences with whisper.cpp (should be in the AUR). I used the large model on my GPU (3060), and it filled 11.5 out of the 12GB of vram, so you might have to settle for a lower tier model. The speed was pretty much real time on my GPU, so it might be quite a bit slower on your CPU, unless the lower tier models are also a lot faster (never tested them due to lack of necessity).
The large model had pretty much perfect accuracy (only 5 or so mistakes in ~40 pages of transcriptions), and that was with Dutch audio recorded on a smartphone. If it can handle my pretty horrible conditions, your audio should (hopefully) be no problem to transcribe.