I took a deeper dive into mod-tapping and home row mods. Absolutely fascinating and useful, even without an ergo/split keyboard.
I put the 'shift' keys on F/J, and 'AltGr' on G/H (for Umlauts with EurKey). I also put some symbols like '{'or '[' and the arrow keys on a second layer and use 'Caps lock' to switch to that layer on hold.
The only downside to is that I have to relearn my layout a little bit which means my typing speed went down considerably.