Wasn't able to find a guide that was really up to date. But here are the steps that I took:
1) Add LinuxServer/MariaDB docker
To do this I used the default settings and ports while adding password in the advanced parameters.
2) Add user to MariaDB
Log in using the servers IP and the port listed in the docker. No issues logging in, then ran the commands:
CREATE USER 'kodi' IDENTIFIED BY 'kodi'
GRANT ALL ON *.* TO 'kodi'
I was able to verify using MySQL workspace that the user does exist.
3) Install new clean version of Kodi
I plan on using headless, but wasn't fully understanding how to add sources, perform library scans on it. I would endevour this on another day (or just copy sources over once mysql is up and running)
4) Add Advancedsettings.xml to userdata
<advancedsettings>
<videodatabase>
<type>mysql</type>
<host>192.168.1.120</host>
<port>3306</port>
<user>kodi</user>
<pass>kodi</pass>
</videodatabase>
<musicdatabase>
<type>mysql</type>
<host>192.168.1.120</host>
<port>3306</port>
<user>kodi</user>
<pass>kodi</pass>
</musicdatabase>
<videolibrary>
<importwatchedstate>true</importwatchedstate>
<importresumepoint>true</importresumepoint>
</videolibrary>
</advancedsettings>
5) Finally, once restarting Kodi, I went in and added a small source to test it. After a quick scan, nothing had been done in MariaDB, and no new connections had been made to the server
Hope that gives a good overview of what I used