Convert Array Into Text And Remove Duplicate Entries From Text In Cell?

I have the following two columns, and would like to obtain for each individual Company, the corresponding Country values excluding duplicates as text in a single cell.

Company 2Country B
Company 2Country C
Company 3Country C
Company 3Country C
Company 5Country A
Company 5Country C
Company 5Country C

For example:
- For Company 2, a cell containing "Country B, Country C"
- For Company 3, a cell containing "Country C"
- For Company 5, a cell containing "Country A, Country C"

I've approached generating an array using an IF statement, as in =IF(INDEX(A1:A8="Company 5",,),INDEX(B1:B8,,)," "), which returns the following array: ={" ";" ";" ";" ";" ";" ";" ";"Country A";"Country C";"Country C";" ";" ";" ";" "}.

The question is: how do I get that array to produce, as text in a cell: "Country A, Country C". Note that the duplicate Country C has been removed.

There are a few "StringConcat" User-defined functions that I've found elsewhere on the internet, but they don't seem to be able to handle to conditionally generated IF Index array, which I would think is key to parsing between Countries corresponding to each Company in the list.