Problem:
Get product custom field data and save to order custom field

Solution:
Assuming that you are Toolset form's commerce then, Toolset Form's commerce offers the hook "cred_commerce_after_order_completed".
=> https://toolset.com/documentation/programmer-reference/cred-commerce-api/#cred_commerce_after_order_completed

With this hook, it has the product_id and based on the product ID, you can get the value of your custom field and it also offers the psot_id. So, what if you try to use the hook and based on the product_id get the value of your desired custom field and then assign it to your post based on the post_id.

Relevant Documentation:

Problem:
The customer asked how to sort the view's results by the number of likes.

Solution:
Guided to select the custom field that the likes plugin use in the view's order by settings.

Relevant Documentation:
https://likebtn.com/en/wordpress-like-button-plugin#sort_posts_by_likes