Can the Pukka 1-shot the Fool?
Yes, it appears the fool can be killed without their ability working if targeted by the pukka

If Pukka is in play, nobody is safe. The Fool and the Sailor can not be protected by their character ability etc. Also, since the Pukka chooses who to kill a full night earlier than normal, it is beneficial for all good players to reveal their characters and information to the group publicly as soon as possible. Sometimes, with other Demons, it can be beneficial for some good players to not reveal who they are, so that the Demon attacks certain players and leaves others alone - but with the Pukka, this is not the case. Reveal everything, and work as a team to bring that pesky poisoner to justice!