Aside from switching between the playback/system control keys and the regular function keys, in macOS the fn key can be used to access keys not available on the keyboard. For example, if a dedicated ⌦ Delete key there isn't present, then fn+⌫ Backspace result in ⌦ Delete.
My problem is that this behaviour doesn't persist for keyboard shortcuts: when used in conjunction with ⌘ Command or ⌃ Control, fn is ignored. This generates a few inconsistencies.
For example, on my 2017 MacBook Pro ⌘ Command+⌫ Backspace will all previous characters in the current line. Given that fn+⌫ Backspace will delete the next character, I would expect ⌘ Command+fn+⌫ Backspace to delete the remaining portion of the line. However, fn gets ignored and this key combination ends up deleting the previous portion of the line.
How can I have access to the "hidden keys" accessible with fn even when ⌘ Command is pressed?