[Otek]

A simple solution that would work on any keyboard (but will be much easier to do on a keyboard that supports custom layout and layers, e.g Ergodox) would be to send small letter of key is pressed under 0.5s (to be tested what value feels best) and capitalized if over this value. After a while it might feel natural to press quickly for a small letter and slightly longer for capitalized

[shae]

The ZSA firmware fork of QMK does this! I don't have it enabled on my moonlander, but many of my friends do.