No need to apologize! I know your preferences are Debian and CLI! And that your true Computer Sci! Me ... am former teacher/coach that got into IT ... and struggled with IT ... still do at times. While I'd like to be a CLI Ninja, not yet ... so a 'crutch' like Webmin does come in handy!
The OP that started this thread has stated it's 'daunting' ... it is, at first, but doable IF ... IF one 'begins with the end in mind' and 'builds' (the moodle comes last ... not first).
1st for me ... choosing the distro and securing distro updates, package manager, and then installing apache, a secure cert, php + extensions + DB server (and securing DB server).
Panel next - Webmin.
Test apache/php/DB server - secure them ... and lastly the xfer of the moodle.
Another concept ... server to server ... not down and then up - a 'push/pull' concept.
What cli tools to 'push' (from old server to new): rsync/scp
What cli tools to 'pull' from new server acquiring from old: wget.
Next up: site backups: tar for code and moodledata: mysqldump for DB. I do that fairly early ... want to keep what gains I have made!
Can remember reading one time someone else's advice ... the most important command one could learn with Linux is 'man' - the online manual for the distro.
That's lots of reading, but well worth the time!
'SoS', Ken