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.