I based my keymap off of that of the Kinesis Advantage, which does have function keys. I have Ctrl + Alt + Super on the thumb clusters, each as their own key.

I based my keymap off of that of the Kinesis Advantage, which does have function keys. I have Ctrl + Alt + Super on the thumb clusters, each as their own key. I did copy the default layout for the Ergo S-1 which uses a modifier key (also on the thumb cluster) to access the function keys, so F1 is Fn+1, F2 is Fn+2. I thought I would miss having dedicated Fn keys but they are surprisingly not missed much in my workflow. Might depend on your workflow though. The current solution is workable, at any rate.