I have never seen a pineapple seed. Maybe they don't exist

I've never seen a pineapple seed either. Living in an area
where they grow pineapples extensively, I can tell you how
they propagate them here. After the pineapple is ripe and
has been harvested, they whack the top of them off and
collect the tops in a big pile. After the field has been
prepared, each top is then stuck through a hole in the
black sheeting (plastic? I've heard it's a special plastic
that degrades quickly, but could be of some other material)
that covers the fields. Don't know if it's the only way
to propagate them, or just the most efficient.

Doesn't answer your question about whether it's a fruit or
not though, does it?

Tracey