Is it safe to disable rsyslog if I have journald?
Solution 1:
It is safe. I have uninstalled rsyslog on all my Debian running personal computers. Yet in such a scenario you have done the right move I believe to change /etc/systemd/journald.conf, line Storage=auto to Storage=persistent to keep older journals, not only the current after boot, which is the default setting in Debian 10.
On the other hand, on servers you could leave it for better handling of logs; perhaps to redirect them to a log server as you mentioned. Since you don't need this feature, you could unistall it or disable it from servers also.