According to Asus, up to 2 M.2 SSDs should be possible:
ROG Strix X570-I Gaming
AMD X570 Mini-ITX gaming motherboard with PCIe 4.0, Aura Sync RGB, Intel Gigabit Network, Wi-Fi 6 (802.11ax), M.2 Audio Combo Card, HDMI 2.0, DisplayPort 1.4, SATA 6Gbit/s, and USB 3.2 Gen2.
AM4 Socket: Ready for AMD Ryzen™ 5000 Series/ 4000 G-Series/ 3000 Series/ 3000 G-Series/ 2000 Series/ 2000 G-Series processors for maximum connectivity and speed with up to two M.2 drives, USB 3.2 Gen2 and AMD StoreMI.
