The ASUS PN41 fits an M.2 SSD and a 2.5-inch drive in a tiny chassis

One M.2 2280 slot (NVMe or SATA) and one 2.5-inch SATA III bay for a 7mm-thick drive. Small form factor PCs rarely give you both an NVMe slot and a SATA bay, so the PN41 earns points for versatility.