Type Alias DeepPartial<T>

DeepPartial: {
    [K in keyof T]?: T[K] extends readonly unknown[]
        ? T[K]
        : T[K] extends object
        | null
            ? DeepPartial<NonNullable<T[K]>> | Extract<T[K], null>
            : T[K]
}

Recursive partial: nested objects become partial too, arrays are replaced whole.