PEXM2-SSD PCIe M.2 Adapter - Supports NVMe/AHCI M.2 SSDs (2280, 2260, 2242) - PCIe 4.0/3.0 Compatible

HDD are way too slow, you will regret it. You need a SSD and an adapter to add an extra. Something like this: https://www.amazon.com/Ableconn-PEXM2-SSD-NGFF-Express-Adapter/dp/B017JGVTAM