I may have to find a new keyboard after Microsoft's Natural Ergonomic Keyboards are gone.

I wrote to Jose Soltren in 2021:

I need a split keyboard, and just discovered there's a wiki at Reddit that mentions a mechanical split keyboard that's in the neighborhood of what my wrists need, the Cloud Nine C989M ErgoFS or ErgoTKL.

A similar keyboard to the Microsoft Natural Ergonomic 4000 is Logitech ERGO K860.

And this Redditor make a note of their upgrade I think I finally found a mechanical replacement for my Microsoft Natural Ergonomic Keyboard 4000 and Surface Ergonomic Keyboard. The Perixx PERIBOARD-835 (835 preferred but also the older 335/535).