Convert pg_constraint.conkey array to same-order array of column names

We have a query returning 1 row per constraint column,
which until recently we didn't realize wasn't preserving order of the
columns.

A colleague fixed that, with something like below:

SELECT ...
FROM pg_catalog.pg_constraint cnstr
...
CROSS JOIN LATERAL UNNEST(cnstr.conkey) WITH ORDINALITY AS cols(value, rank)
ORDER BY cols.rank

But I'm wondering about getting 1 row per constraint instead,
and fetching an array of column names.

So is there a way to "convert" int2[] conkey array into a text[] of those
column names?