I'm surprised how easy it was to add an entry to the context menu in the file explorer on Linux. At least on Nemo, you just need to create a .nemo_action file at ~/.local/share/nemo/actions/ and fill it with basic info such as the executable path, label, icon, file extensions, etc.
I thought it was going to be a pain in the ass like on Windows, where you have to mess with the registry, and if you want to handle that shit via code, you'd most likely need a specific library for it.