Put a specific word in a cell based on the word in another cell

I only consider using 365, preferably insider beta.

My strategy is to search for the presence of each merchant within the description, returning the corresponding category where successful.  Because there is the possibility that more than one merchant could be present on a single row, concatenation reduces the categories to a scalar.  This reverse lookup is given by

Worksheet formula
= REVLOOKUPλ(description, merchant, category)

where

REVLOOKUPλ = LAMBDA(descr, merch, cat,
    MAP(descr, LAMBDA(d, 
        CONCAT(
            MAP(merch, cat, LAMBDA(m, c, 
                XLOOKUP(m, d, c, "", 3))
            )
        )
    ))
);