Filter a record based on user condition

Hi! I have developed a site and I want it to be filtered for each user based on its condition (supplier name). Basically, my idea is to use the site as a "Supplier Portal", so each supplier can only see its own Purchase orders and invoices. To be clear, I want this:

- User 1 is the supplier 1 in real life. I want Appian to know that he is Supplier 1, and filter the records with this condition (in the record it would be nomProveedor = Supplier1)

I have thought about the options but I would want your expertise and advice:

1) Create a record type (username - supplier), and use this information to filter the record (I have doubts on the steps to achieve the supplier field based on the username and how to put it into a filter/query. 

2) Create a previous interface in which the user identifies himself with the supplier name (F.e. supplier 1) , and use this variable to filter

3) Create a group for each supplier and give permissions (it would be fine for 3 or 4 suppliers, but not viable for a lot of suppliers)

Any help would be useful!  Thank you so much

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