Yes, deb.torproject.org is also served through via an Onion Service: http://sdscoq7snqtznauu.onion/

Note: The symbol # refers to running the code as root. This means you should have access to a user account with system administration privileges, e.g your user should be in the sudo group.

To use Apt over Tor, the apt transport needs to be installed:

   # apt install apt-transport-tor

Then you need to add the following entries to /etc/apt/sources.list or a new file in /etc/apt/sources.list.d/:

   # For the stable version.
   deb tor://sdscoq7snqtznauu.onion/torproject.org <DISTRIBUTION> main

   # For the unstable version.
   deb tor://sdscoq7snqtznauu.onion/torproject.org tor-nightly-master-<DISTRIBUTION> main

Replace <DISTRIBUTION> with your Operating System codename. Run lsb_release -c or cat /etc/debian_version to check the Operating System version.

Now refresh your sources and try to install tor again:

   # apt update
   # apt install tor