finding apt dependencies

I have a need to find the upgradable package with the most dependencies. 
  So far I've got this, in /bin/sh:

allpkgs="$(apt list --upgradable 2> /dev/null | grep / | cut -f 1 -d / )"
max=0
countlist=""
for package in $allpkgs ; do
   dependencies=$(apt-get --simulate upgrade "$package" | grep upgraded, 
| cut -f 1 -d ' ') # get #dependencies, maybe; this is the slow bit
   [ "$dependencies" -gt "$max" ] && max="$dependencies"
   countlist="$countlist $dependencies $pkgname"
done

It works, but is definitely not fast. Is there a faster way?