It is never smart to assume functionality. The code:
get_field('related_products', 'id') will not work. Please always read the documentation which has been written for you to understand what parameters are available.
The page link field is very basic and will only return a url, nothing more. If you wish to get the title as well, you will need to change the field type to post_object. This will use the same data as page_link (so you will not lose any data) but your code will obviously have to change to allow for the new returned data.
Please read the docs to learn more about this field type
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