Ax23 vs C6U for general use

The c6u has the option to extend the miniscule 16mb(8mb) flash with a USB drive while the AX23 does not, with the same flash size.

I live in a rather closed off environment so WPA3 isn't a big requirement and I think I could get away with WPA2.

The AX23 is is 3.7K INR right now, while the C6U is 2.5K INR.

Why would anyone chose the the AX23 since they have the same chipset, same number of antennas, flash, ram, etc.

My use is a basic home router which is connected to my ISP router, I don't use VPNs or anything but would like monitoring packages hence need some space.

What am I missing?

What you're missing is the wireless protocol. AX23 is - as it names suggests - 802.11ax, and the C6U is 802.11ac. Besides that, the MT7613 in the C6U is a problematic radio on OpenWrt. The red-headed stepbrother of the MT7615, so to speak.