buy a kingston, samsung or reputable brand 256gb SSD should give you more than enough endurance for just 40gb a day
Edit: especially since 40gb a day for 5ish years is only like 70 TB written, which even the cheapest SSDs can sustain just fine, it is hard to find an ssd rated for less than 150 TB lifetime
Whether this cache is being used for a local system or a network attached systemm, there is no point in getting an SSD of only 16/32GB, no matter the speed of the drive (unless it’s RAM speeds, which drives aren’t yet, aside from RAM cache drives).
Get yourself some name-brand (Corsair, Sandisk, Samsung, SK Hynix, Kingston, Micron, etc.) PCIe M.2 SSD (NVME) of 256/512GB, and use the drive as a cache AND frequently querried data storage drive. You’ll get a much better performance increase from that, in comparison to a tiny 16/32GB cache drive, because it’ll (most likely) constantly be pulling data from a slow ass HDD.
Even if you have 0 plans of using the rest of the storage (or your use case simply can’t FOR WHATEVER REAOSN), you can at least reuse the drive in a couple years, while in a couple years, that Intel Optame drive will be useless.