OpenWrt One WiFi 6 router samples are now available for $89

Probably

Full specs:

• 1GB DDR4 memory (onboard)
• 256MiB SPI NAND Flash and 16 MiB SPI NOR flash storage
• M.2 2242/2230 socket for PCIe Gen  2 x1 SSD (bring your own storage)
• MediaTek MT7976C dual-band WiFi 6 support (2×2 2.4 GHz and 3×3 5 GHz)
• 1 x USB 2.0 Type-A host port
• 1 x USB Type-C (device, console)
• RTC backup battery support
• PoE support
• MikroBUS socket for expansion modules

It has a USB port and an M2 NVME slot. As someone else noted, USB is usually considered a poor choice due to speed and reliability, so I would suggest nvme.

Setting up NAS? Anything over USB is going to be slower than LAN, isn't it (which is still your bottleneck anyway)?