I should provide an update for this... It Works.
My hardware is as follows: (built shortly after this post)
the linked motherboard-CPU combo (unit?) above (thermalright AXP90 cooler)
32 GB of DDR4
LSI 9240-8I HBA
3 (now 4) 4tB Seagate Ironwolf Pro HDDs (fourth was added a week or so ago with little fanfare)
Jonsbo N4 (with an additional fan on a 3D printed stand for the HBA)
silverstone 450w SFX PSU
After building the system i did quite a bit of tinkering, i am running the following services:
Immich, Jellyfin, Jellyseer, pihole, portainer, tailscale and a some VMs
The above taken into account, i have spent a fair amount of time within the TrueNAS UI which is both less and more intimidating than its reputation indicates.
Let me know if you have any questions (i will do my best to answer them).