There's a whole sub community online that builds custom ergonomic boards. They are often split (two halves) for better positioning and you can tilt and tent them.

For example, have a look at the Dactyl Manuform or its variants (eg Tightyl), the kyria or corne.

An exciting new development in the homebuilt keyboard scene is Bluetooth controllers, so the ecosystem is starting to embrace wireless too! Look for nice!nano.