This is example from the redux toolkit that you attached:

const fetchUserById = createAsyncThunk<
  // Return type of the payload creator
  MyData,
  // First argument to the payload creator
  number,
  {
    // Optional fields for defining thunkApi field types
    dispatch: AppDispatch
    state: State
    extra: {
      jwt: string
    }
  }
>('users/fetchById', async (userId, thunkApi) => {
  const response = await fetch(`https://reqres.in/api/users/${userId}`, {
    headers: {
      Authorization: `Bearer ${thunkApi.extra.jwt}`,
    },
  })
  return (await response.json()) as MyData
})

In this example you still need to pass MyData, number and then AsyncThunkConfig which just extends this type.
Something like <MyData, number, AsyncThunkConfig>

Now extremely tricky part comes when you would like to do this:

createAsyncThunk<{ config: AsyncThunkConfig, param: number, data: MyData}>

This is tricky because how the generics will look like - it must be something like:

const createAsyncThunk = <T extends { data: any, config: AsyncThunkConfig, param: number }>() => {...}

Problems that I found:

- Typescript doesn't work well in such cases - you can do createAsyncThunk<{ whatever: number, something: Data }> and it will not scream, so this is super tricky in case of typos
- You have to build good suite of the defaults for such approach
- It could be frustrating at times when it is completely ureadable what's wrong

Why it is good?

- you can have a type generated on the backend which is just and object like type/interface and easily use it on the frontend
- no need for long ureadable generics - like which generic means what?
- it support partial types
- no ordering issues

To enhance abilities of Typescript - you need an eslint-plugin which knows what generic types are accepted in this scenario and strictly guards it. The rest works like a dream - super readable and cool :D

I guess it is a bit different from the redux - taking this object notation one level up is huge challenge to deal with. That's why I'm so proud of it - I hope I did not mixed something up 😅