Just for the record, if you'd done a thorough search you'd have seen me say this in January:
" For a very long time I've been using the ⌥ key to trigger macros. Here's an example showing the left and right Option keys double-tapped being used as a trigger"
in this post: Double Tap Cmd/Opt/Shift/Control as Hotkeys - #4 by tiffle
Of course, I added the caveat that I didn't know if the approach worked without an external keyboard, but for those who do use one now you know!