Dynamically create an object with keys based on type

I have this code:

type Foo = {
  fiz: 'baz',
  bar: 'biz'
}

const foo: Partial<Foo> = {}

Essentially, the type will change a lot, and I want to do smth like this:

Object.keys(Foo).map(key=>{
  foo[key] = null;
})

But that’s obviously impossible. Is there a way to make it work dynamically? Or am I stuck with typing each key dynamically?

Link to playground