Under-bed shotgun safe?

Not sure what your budget looks like but the snap safe under bad safe might fit your needs. Or hornady's AR gunlocker might work depending on your shotguns size.

V-Line and Benelli M1S90, before I switched to an AR for HD:



I use a 3 button code on the simplex lock. Same code for my CCW case and my nightstand gun.

Same setup with current gun:

Love those photos!
I use a Mini 14 in mine in a Pelican case, (water proof, airtight, only downside is it takes 4 snap tight handles to open it.)
It is not fast

Santa Cruz makes some interesting options.
http://santacruzgunlocks.com/products/

I don’t have anyone in the house younger than myself. I keep mine in the closet, in cruiser ready mode (mag loaded, trigger pulled so all I need to do is pump the action once). It may seem like a novelty, but on the buttstock I taped a big sign saying “Gun is loaded, do not touch!!”

Edit: I read the Question wrong, whoops

I think lucky Gunner did a video on this a year or so back. Don't have the time to look it up but had a few acceptable options.