Yeah it is just RAM and SSD that it needs. You can but them pre-built with RAM and SSDs already included and if you do look for something 2nd hand or refurb then it may already have them.
Discussion
Sort of not keen on refurb one just in case. Given what’s at stake
I’d probably at least put a new SSD in with a refurb. It’s easy enough to move that to another box if the box dies but much harder to recover if the SSD dies. Still need backups either way though as even new devices can die.