And that is the core of the problem. Your buying a storage media that is a lot slower in sequential read/write, and also on random's. But your paying the price of the superior m.2 NVME's.
SSDs need to sit more between HDD/NVME's, but they are on the same level as NVME.
Another issue, is just like with 2.5" drives, you see manufactures really only focus on specific drives. Its going to be 3.5" or U.2/U.3 and now NVME NAS solutions. But you do see any 2.5" / SATA solutions?
I mean, the only thing i remember seeing is the Synology DiskStation DS620slim that is now like 5 years old product. And still expensive as hell. Nobody makes any SATA products.
The market is now being a ton of Chinese brands / mini-pc makers that offer 4, 5, 6 NVME products. And even with PCIe3.0 x1 lane support, they are faster then SATA SSDs. And benefit from the massive better random/lower latency.
I love to shove a ton of SATA SSDs in a system, instead of HDDs but the prices need to be somewhere in the middle of HDD/NVMEs per TB. Not the same as NVMEs.