What would be useful as well: I'd like to be able to add more regular keys to the main section. That's not supported as of now, is it?

No, it's not supported right now. Would you mind to present an use case where such additional keys will not be the ones added by the libappimage registerApplication method?

No, it's not supported right now. Would you mind to present an use case where such additional keys will not be the ones added by the libappimage registerApplication method?

For example when writing the version of AppImageLauncher into a desktop file, which can be useful for debugging, or some hashes that have a meaning to AppImageLauncher (in the future I plan to add some features that require this kind of stuff).

Those are very AIL specific things but seems reasonable to be able to add the capability of adding custom keys.

what about:

void registerAppImage(const core::AppImage& appImage,
                                        std::unordered_map<std::string, std::string> additionalEntries = {},
                                        std::unordered_map<std::string, std::string> additionalApplicationActions  = {}) const;