The openwrt config for the a10s doesn't exist, I tried to appropriately edit the config to include the device but it's a bit more confusing than the one on armbian where I simply combined the appropriate parts from both the a10 and a13 configs plus the correct u-boot defconfig into a single valid config and it worked.
sunxi based devices generally should be rather easy to add, as they're 'unbrickable' SBCs with pretty good mainline support (including the DTS). While it will still need its own bespoke image (as explained by frollic above), getting that to work (and potentially merged later on) should be pretty realistic (and much easier than for most 'normal plastic routers'), but it needs to be done nevertheless.
Should be straight forward. See these commits for minimal examples:
You might also need to add the board to package/boot/uboot-sunxi/Makefile