I have spent significant time trying to figure out what should be the standard apt sources.list files. Finally, I found it (listed right there on the Devuan web site). This is current as of 2021, but go to https://www.devuan.org/os/packages for the “true” list.

Beowulf

deb http://deb.devuan.org/merged beowulf          main
deb http://deb.devuan.org/merged beowulf-updates  main
deb http://deb.devuan.org/merged beowulf-security main

ASCII

deb http://deb.devuan.org/merged ascii          main
deb http://deb.devuan.org/merged ascii-updates  main
deb http://deb.devuan.org/merged ascii-security main

Jessie

deb http://archive.devuan.org/merged jessie          main
deb http://archive.devuan.org/merged jessie-updates  main
deb http://archive.devuan.org/merged jessie-security main

Same thing for Zabbix. It is sitting somewhere out there on the zabbix web site, but https://tecadmin.net/install-zabbix-agent-on-debian/ has it also.

## For Debian 10:
 
wget https://repo.zabbix.com/zabbix/4.0/debian/pool/main/z/zabbix-release/zabbix-release_4.0-3+buster_all.deb
sudo dpkg -i zabbix-release_4.0-3+buster_all.deb
 
## For Debian 9:
 
wget https://repo.zabbix.com/zabbix/4.0/debian/pool/main/z/zabbix-release/zabbix-release_4.0-3+stretch_all.deb
sudo dpkg -i zabbix-release_4.0-3+stretch_all.deb
 
## For Debian 8:
 
wget https://repo.zabbix.com/zabbix/4.0/debian/pool/main/z/zabbix-release/zabbix-release_4.0-3+jessie_all.deb
sudo dpkg -i zabbix-release_4.0-3+jessie_all.deb