Hi Eric,
For package selection/ removal, I followed the guidelines on this link: https://openwrt.org/docs/guide-user/additional-software/saving_space
Then started building images on this image builder page: https://firmware-selector.openwrt.org/
Then under INSTALLED PACKAGES i made it work with the following selection/ removal of packages:
base-files ca-bundle dnsmasq dropbear firewall4 fstools kmod-gpio-button-hotplug kmod-leds-gpio kmod-mt7603 kmod-nft-offload libc libgcc libustream-mbedtls logd mtd netifd nftables odhcp6c odhcpd-ipv6only opkg ppp ppp-mod-pppoe swconfig uci uclient-fetch urandom-seed urngd wpad-basic-mbedtls kmod-mt7615e kmod-mt7663-firmware-ap kmod-usb2 kmod-usb-ohci kmod-usb-ledtrig-usbport -ppp -ppp-mod-pppoe -ip6tables -odhcp6c -kmod-ipv6 -kmod-ip6tables -odhcpd-ipv6only -odhcpd -iptables uhttpd uhttpd-mod-ubus libiwinfo-lua luci-base luci-app-firewall luci-mod-admin-full luci-theme-bootstrap luci-proto-relay -opkg
The above can be copied directly into the image builder and should work with both, 902AC V3 or 902AC V4 as the first thing one selects is the model of the router/ AP. The rest is the same.
This removes the all IPV6 related packages, DHCP server, opkg, adds basic luci interface and the relayd packages.