Thinkpads are extremely well documented. For how to repair/replace parts, you need the HMM. Just Google for “Thinkpad t14 Gen 1 HMM” and you should find the official PDF on their site. That will tell you, step by step, how to replace the keyboard.
As for the part itself, you can again check Lenovo’s site for all compatible parts (FRUs) and find the item number and details. While I wouldn’t recommend buying directly from them due to cost, this should give you the information needed to find it elsewhere. eBay has tons of Thinkpads being sold for parts, and many of these will be parted out. You should have no issues finding what you’re looking for.
I found the specs a bit interesting. 52.7 kWh battery and a curb weight of 3,600 lbs is nearly identical to the Chevy Bolt, but this only has a range of 150 miles instead of 240. Is it really that much less efficient? The only thing I can think of is the aerodynamics, but that’s a 40% difference.