They exist but are expensive and tend to only be on sale for short periods of time in group guys, for example the Rama Zenith

https://ramaworks.store/products/zenith-keyboard

The Kinesis Freestyle Edge has 12 such keys in that position. The mechanical gaming version (RGB) allows them all to be arbitrarily mapped, and function keys are one good use of them.

Thanks - both your suggestion and @davewongillies are close ... but my ideal keyboard is still the "87 key" layout with the inverted T, but with 12 function keys on the left. On modern PCs it's hard to live without the F11 and F12 keys.

I'd even settle for a 12 key keypad on the left as well - that might be more doable. Looks like I might have to build this myself from scratch ...

There are a few commercial keyboards out there that offer this. I was going to suggest the Logitech G110 that I use, but it appears that model's no longer manufactured. Still, there are others.

What do the F11 and F12 keys do for you on a modern PC? I don't know of their uses offhand.

F11 is often fullscreen, and F12 is sometimes a screenshot button in some games.

If using a debugger with Visual Studio-type keyboard shortcuts, F11 = step in, Shift+F11 = step out.

If running under the Visual Studio debugger, you can also press F12 with the debuggee in focus to break into the process.

I use F12 several dozen times per day because it is the "Save as..." shortcut in MS Office. Much better and quicker than navigating the menus

Full screen and dev tools respectively for web developers.