Yes it is “Possible” !
If you have a MacBook pro early 2020 base model (AKA A2289 / MXK32,MXK62 LL/A) it is possible only to swap logic boards and heatsink and get it working. Nothing more. The connectors and their locations and types are exactly the same.
You need both the logic board and the heatsink though. The rest of the device is the same as the M1 upgraded model.
I checked both M1 and my own MXK32 MacBook logic boards and they both fit each other’s casings.
After I saw this thread, I made an account here only to share this with you. If you have a baseline MacBook pro early 2020, you can open it and check it against an M1 MacBook pro to confirm it for yourselves. I attach images below. One is M1 and the other is my A2289 - MXK32LL/A