Hi, Same Project you have Posted in Other task too. Please find my comment below.
We could insert directly into database.
If external system in PHP means, we could directly insert into woocommerce database. Else, we could pass the Product information to woocommerce website and we could get and insert Product information from woocommerce site itself.
For product insert Process we could Use below Functions and more.
1. wp_insert_post ---- We could use this function to insert the basic Product information into database.
2. update_post_meta ----- We could use this function to insert information like _stock_status, _regular_price, _sale_price, _purchase_note, _sku....etc.
Also, we could insert Product variations too Using "product_variation" Post Type.
Only woocommerce Database understandable person could do this. I will do it for you.
I will start to work, Once you select me. No waiting time.
I am working for Good Reviews. So, surely you will get good support from my end more than what you are expecting.
Thank you.