You could quite easily use a t420 keyboard in a t440 with a few pins masked which was the last traditional thinkpad keyboard.
Actually I may be getting the numbers wrong, it could be the t430 that I was thinking about. It's been rather a long time since I did any brain surgery on thinkpads.
Hows the build quality with framework laptops? I fear that making it so modular might have required engineering tradeoffs with regard to build quality and endurance.
I got one in March 2022 and it's still kicking. Had to replace the heat sink and the keyboard this year. The support is kinda slow on the response, but the hardware itself is pretty nice.
There hasn't been a decent one since the t440 and the only way to get that to a good standard was by modding the hell out of it.
The t61 was the last good one.
Framework is not quite at that quality but it's better than any other laptop made in the last 10 years.