In order to assign all products to the website please, go to your Magento 2 Admin panel > Catalog > Product and Select All products.
Then, choose Update Attributes in the Actions select box.
Afterwards, move to the Product Information > Websites and in the Add Product to Websites section, choose the website you need.
Next, press the Save button.
Wait some time. After a while, you'll see the notification about the assignation being performed.