You can solve this without layers on the Moonlander, or any keyboard that allows you to load your own firmware.
For instance, you could configure your number keys to have a "press and hold" generate the corresponding F key. The 'hold' doesn't have to be very long to still easily distinguish it from "normal" typing.
You could also make it a key combo very easily. Anyone who doesn't like key combos should take up a war against !@#$%^&*()+_?:<>{} and their friends.
Hold? No thanks. How does that work when you are debugging code and have to repeatedly press the step over button. Both VS and IntellJ use F-keys as default for this. With lots of shift-modifiers already, to toggle step in, over, out.
For instance, you could configure your number keys to have a "press and hold" generate the corresponding F key. The 'hold' doesn't have to be very long to still easily distinguish it from "normal" typing.
You could also make it a key combo very easily. Anyone who doesn't like key combos should take up a war against !@#$%^&*()+_?:<>{} and their friends.