There is no need to smash your computer after generating your Bitcoin keys/seeds
Also you can run your Live system on USB flash drive but without activating the swap and in read only mode (without writing your home directory on the flash drive). If you are very paranoid you can use one of these USB flash drives with hardware write protection. Or just buy DVD drive without writing capability (if you don't have one) - it's read only for sure.
After you restart (an if you are very paranoid - after running memtest86+ for several hours) it is safe. Unless there is a malware in your UEFI/BIOS... Or inside the CPU itself.
This is why you should use the oldest computer possible - they are less probably to have malware on their CPU.