Today I uploaded the Add Multiple Product in Product Listing for 2.3.1 v.1.0
This contribution provide another replacement for the standard product listing module.
It allows the customer to submit multiple products, with multiple quantities per product.
It will give you input field for every item with plus/minus button
Use this thread for upgrades, comments etc.
I hope somebody will make the attributes work as the first upgrade.
find it here Add Multiple Product in Product Listing for 2.3.1