If I had to start again today the new beelink Me Mini is tempting. Intel N150 CPU and six 2280 SSD slots.
Discussion
Doesn’t look like it can RAID and limited to m.2 SSD?
The idea is you install something like truenas on the tiny 64gb drive and let it take care of raid.
And yes, only M2 but they do come in 8tb these days. Or are you looking at a monster 3.5 inch setup with loads of 30tb drives?