This is where you really are supposed to have an isolation transformer of some kind between the A/C line voltage and your project.

Even if the transformer is 1:1 ratio so your project gets the full line voltage, a physically small transformer will physically limit the amount of current available to the project.

May still be enough current to kill you but it should be less than the full amount available directly from the building's circuit breaker.

Then you always want to have fuses with lower amperage ratings than the transformer, just enough for your project or product to run while being protected in case of fault.