ErgoMechKeyboards

At the budget end, Perrix makes the Periboard 535 which is certainly superficially similar. The Perrix is limited as a customizable mech, but if it is what your wrists and hands need, it may be good. I'm not sure if the choc switches are hot-swap, and good luck finding aftermarket keycaps, but you can at least choose from clicky, linear, or tactile.

If you want to drift away from a Microsoft style, several companies make "Alice" mechanical keyboards which are split and slightly tented, and allow more enthusiast options, but you'd have to get an external numpad if you need one.

I started out on a similar place and started with the truly ergonomic keyboard. It has a weirder layout then what it was when I bought it more then ten years ago.

I will say I’ve owned two of these boards, the first version used Cherry browns and still works great, the second one I got for work used something else besides cherry and was missing keystrokes in under a year. I believe they are using completely different switches now.

X-Bows has some keyboards that look more ergonomic with pinky column stagger and splay but still a full complement of keys in a mostly traditional layout. Disclaimer: I've never used one as I was past that stage when it came out.

Dygma is probably a good place to look. They're slightly "weirder" than your microsoft board, but still fairly close to a traditional layout. They're also a bit smaller, but configurability of the keymap completely compensates for that imho. But being actually split, with some extra thumb keys, is a good step up in ergonomics from the microsoft I think.

I really like the Kinesis Freestyle Pro (I got the gaming one with RGB lights) with the extra tents to give the same slope from the Natural 4000

https://kinesis-ergo.com/shop/freestyle-pro/