No, that's a completely different thing - an index access method, building a bloom filter on multiple columns of a single row. Which means a query then can have an equality condition on any of the columns.

That being said, building a bloom/cuckoo filter as a data type would be quite trivial - a basic version might take an hour or two, the more advanced stuff (to support partial aggregates etc) might take a bit more. Ultimately, this is not that different from what postgresql-hll does.