From a pure cost point of view, I think it still makes sense to me to split the load, like 500GB of NVMe covers your containers and apps and stuff, but then 10-20TB of spinning storage is fairly achievable with redundancy, whereas that would cost a fortune to do as all solid state.

The case I have is a Jonsbo N2, which works great for accommodating 5 3.5" drives with backplane, a mini-ITX mobo: https://www.amazon.ca/N2-Aluminum-Support-Integrated-Removab...