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apt-move

apt-move moves the cache of Debian packages into a mirror hierarchy.

Installing

$ sudo apt install -y apt-move

/usr/lib/apt-move/fetch

/usr/libapt-move/fetch is a binary to fetch files just like apt-get install -d, except that no dependency analysis is done.
A comment in apt-move refers to the binary /usr/lib/apt-move/fetch as the crappy replacement for apt-get.
Apparently, this binary can be used to find out the URL of a package: 
$ sudo /usr/lib/apt-move/fetch -t python3
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
http://deb.debian.org/debian/pool/main/p/python3-defaults/python3_3.9.2-3_amd64.deb

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