Alternative layouts are a risky field because people have totally different typing habits. So you cannot really talk about layouts in general, nor evaluate them, without knowing the user.
That's why I try to avoid advocating layouts – even my own one. ;)
However, there's a quite obvious and risk-free modification: numbers.
The gist of the trick is that the frequency of numbers is different but sort of descending: 0123 are the most frequently used ones and 789 are much rarer.
Well, it depends on the corpus but in the author's experience the order is 1023456879. I know of some hardcore layout-geeks who would arrange their numpads that way but for the sake of learnability we can group the digits, and the result is something like this:
So with numbers on a logical layer, instead of putting 456 on the home row (as it's done on the classic numpad) you can put 123 (Pnohty) or 0123 (my approach) in the best positions:
With Pnohty, the numpad is arranged in almost the same way as I've used it for more than a year now. I tried to find the old blog post I read about this for the first time – without success. Will update this post if I find it.
The point is: In programming, many short ordered lists, array indices, etc. may end at 3 so you can do a lot of stuff on the home row.
I type a lot of dates, even datetime values, so e.g. being able to type today's date (2022-01-30) exclusively on the home row is important for me.
That's it. Try it out. It takes some time to retrain your muscles though. I found it more challenging than getting accustomed to swapped alphas – probably because numbers are used less often and sporadic.
I don't want to comment on the other features of Pnohty, those depend more on your workflow and typing habits.
There are two completely different keyboard matrices referred to as duplex matrix. Let's examine the Japanese one, which makes possible to handle 160-200 keys with a single Pro Micro.