I recently swapped the mainboard of my T420, it was quite easy to do with just a screwdriver (and the maintenance manual and some thermal grease). Extended this

I recently swapped the mainboard of my T420, it was quite easy to do with just a screwdriver (and the maintenance manual and some thermal grease). Extended this five year old machine's life by another year or so for ~50€. It was very easy to do with the manual. I'm not sure how much harder it is with the newer models, but maybe a ThinkPad meets your requirements better than a MacBook?