Change all unique country abbreviations to country names and place in one cell

I need a formula that can add all the countries with that is in a column.

Example:
In sheet 'Export' I have the below countries of origin:

And in other sheet I need to show all the countries of origin and change the name from RO to Romania or SK to Slovakia, etc...

What I have until now is the formula:

=TEXTJOIN(", ",TRUE, IF(left(Export!Q1,2) = "RO" , "ROMANIA", IF(left(Export!Q1,2) = "US" , "USA", IF(left(Export!Q1,2) = "PT" , "PORTUGALIA", IF(left(Export!Q1,2) = "FR" , "FRANTA", IF(LEFT(Export!Q1,2) = "SK" , "SLOVACIA"))))))

But is not working. It only shows the first country found, not all of them.

Can anyone help?

Link: https://docs.google.com/spreadsheets/d/1-Iz0K-tKKjuur6eF3tvEiEJP6zLjm8tAl0RXZqOwX9M/edit?usp=sharing