Funcy，it not appeared in Duo S which boot from Arm。
Searching for ‘i2c’ in the device-tree, I saw that the state of i2c0 is ‘disabled’ (build/boards/cv181x/sg2000_milkv_duos_glibc_arm64_sd/dts_arm64/sg2000_milkv_duos_glibc_arm64_sd.dts)， so I didn’t see the ‘/dev/i2c0’ in the device。
i2cdetect command with options ‘-r’ means MODE_READ, you can try to run ‘ls -al /sys/bus/i2c/devices/’ and list all i2c devcie。