i have shown work matted ( 4ply backboard and 8 ply windows, NOT drymounted ) in archival boxes ..
i have also shown in a leather bound presentation book, and i have shown loose prints,
and web-images. it all depends on the gallery and what their expectations are.
some galleries want to see the work unframed / unmatted. they will pay for all framing and matting themselves.
others want to see the whole presentation ahead of time. when i part owned a gallery years ago ( in the 90s )
we didn't care one way or another, we had expectations that the artist present his / her work in a professional manner and they did.
good luck with trying to get representation .. from the galleries i have spoken with in the last few months
it is a very-difficult time and many aren't even looking at "new work" for 18+months ...
maybe that is just my neck of the woods ( boston + new york )
have fun !