REST API: How do you get the SKU for items in a grouped product?

I’m able to create, update, delete and fetch products using the REST API, the problem is that when I find a grouped product I need to also get the SKU that belong inside that grouped product, I see them fine in the GUI, but I can’t seem to find a method that returns these values in the API.

This is where I find the grouped items when editing the product on the GUI

but this is what I get when I query the same product via the API (end point
/rest/V1/products/mySku)

{
    "id": 163664,
    "sku": "mySku",
    "name": "some product name",
    "attribute_set_id": 4,
    "status": 1,
    "visibility": 4,
    "type_id": "grouped",
    "created_at": "2020-03-30 07:31:03",
    "updated_at": "2020-03-30 07:38:45",
    "extension_attributes": {
        "website_ids": [
            1
        ],
        "category_links": [
            {
                "position": 0,
                "category_id": "278"
            },
            {
                "position": 0,
                "category_id": "279"
            }
        ]
    },
    "product_links": [],
    "options": [],
    "media_gallery_entries": [],
    "tier_prices": [],
    "custom_attributes": [
        {
            "attribute_code": "image",
            "value": "no_selection"
        },
        {
            "attribute_code": "url_key",
            "value": "mySku"
        },
        {
            "attribute_code": "diameter",
            "value": "5726"
        },
        {
            "attribute_code": "small_image",
            "value": "no_selection"
        },
        {
            "attribute_code": "meta_title",
            "value": "Meta Title"
        },
        {
            "attribute_code": "options_container",
            "value": "container2"
        },
        {
            "attribute_code": "lug_count",
            "value": "6275"
        },
        {
            "attribute_code": "meta_keyword",
            "value": "meta1, meta2, meta6"
        },
        {
            "attribute_code": "brand",
            "value": "5834"
        },
        {
            "attribute_code": "thumbnail",
            "value": "no_selection"
        },
        {
            "attribute_code": "meta_description",
            "value": "meta description"
        },
        {
            "attribute_code": "width",
            "value": "5710"
        },
        {
            "attribute_code": "width_rear",
            "value": "5746"
        },
        {
            "attribute_code": "wheel_color",
            "value": "6384"
        },
        {
            "attribute_code": "bolt_circle_diameter",
            "value": "6359"
        },
        {
            "attribute_code": "diameter_rear",
            "value": "6406"
        },
        {
            "attribute_code": "offset",
            "value": "6335,6354,6328,6350,6333,6355,6338,6343,6353"
        },
        {
            "attribute_code": "color",
            "value": "49"
        },
        {
            "attribute_code": "setup_type",
            "value": "6512"
        },
        {
            "attribute_code": "offset_rear",
            "value": "6716,6724,6714,6699,6729,6709,6704,6719,6726"
        },
        {
            "attribute_code": "category_ids",
            "value": [
                "278",
                "279"
            ]
        },
        {
            "attribute_code": "required_options",
            "value": "0"
        },
        {
            "attribute_code": "has_options",
            "value": "0"
        }
    ]
}

I’m fairly certain there must be another end point that I need to query, I just have no idea which one that may be. Any assistance will be greatly appreciated.