ASUS PN50 — one M.2 and one 2.5-inch bay, no room for more

The PN50 comes with one M.2 NVMe slot and one 2.5-inch SATA bay — that’s it for storage expansion. There’s also an M.2 2230 slot for a wireless card (usually pre-installed), but no additional M.2 or SATA slots beyond what’s already there.