OpenWRT/LEDE uses the
typical /etc/config/network methodology. This defines each interface independently. As such, the wired interface can be explicitly set at a fixed IP, and the wifi can either be configured to grab a DHCP address from an access point, or to provide DHCP addresses in access point mode, and the two will not interfere with each other. It's just a few bytes of config file away.
The wireless device is further controlled with
/etc/config/wireless, and DHCP rules are defined in
/etc/config/dhcp.
By default, LEDE/OpenWRT disables the wireless interface for security reasons. It is fairly painless to turn back on, and should be possible to alter in the build process's root tree structure in the /target folder of the source package. As such, it should be possible to build a flashable image with the appropriate changes already baked in at basically 0 additional cost.