It is a toaster that can be used as a gun. Burnt toast does damage and toasty/normally cooked toast can heal (it is shot at people and if they eat it they will heal 1d4+ 2 hit points) It cannot be noticed when around other kitchen utensils. It makes a ding sound when fired.
It’s up to you to decide whether a character has proficiency with a firearm. Characters in most D&D worlds wouldn’t have such proficiency. During their downtime, characters can use the training rules in the Player’s Handbook to acquire proficiency, assuming that they have enough ammunition to keep the weapons working while mastering their use.
This weapon has the following mastery property. To use this property, you must have a feature that lets you use it.
Push. If you hit a creature with this weapon, you can push the creature up to 10 feet straight away from yourself if it is Large or smaller.
Notes: Damage: Fire, Damage, Combat, Range, Two-Handed, Ammunition (Firearms), Reload, Push