Check out XY Tech who build and distribute modified ThinkPads. Xue Yao, the person behind it, intends to build a motherboard that will fit into an X220 case soon, possibly this year.
I bought an "X2100" (a ThinkPad X200 with a 10th-gen Intel CPU) from him in 2020 and it's been fantastic.
I bought an "X2100" (a ThinkPad X200 with a 10th-gen Intel CPU) from him in 2020 and it's been fantastic.
https://xyte.ch