If it's done properly, I don't see why not. The only thing that might get in the way will be if there's an individual bms system in each cell that handshakes with the "central" system. I haven't actually cut into batteries in a while, generally only replace them

Ah excuse me I misunderstood the original intent. I can't pretend I understand your reasoning, as it sounds like a very non portable solution for a device that was sold on the basis of portability.

I would probably recommend buying the replacement battery and attempting to remove BMS from that rather than mess about with the spicy pillow

I wouldn't bother attempting to create your own battery. Personally I would attempt to buy a battery from a reputed vendor (original is better but does not have to be), and if you have prior experience dealing with fire risk batteries, go full send next to a bucket of sand.

If its your first time, pay a reputed repaid shop, and start off with another, less risky repair

Wouldn't be something I'd risk to save a couple hundred tbh. If the swollen cell is far enough away from it, maybe? If its badly ballooning, don't bother.

I don't have the pinout to hand, but it's fairly moot as you would need to move the BMS from the old battery to the new. Unless it handshakes, it won't receive power. Microsoft surfaces don't like receiving power at all without the BMs connected