The simplest way to accomplish building a custom firewall is @dlakelan's approach: Retain LuCI and the OpenWRT Kernel. By removing iptables and implementing nftables the cake sqm is fully coded. Simply remove and replace the firewall code.
Things are moving slowly but progress is happening. I will begin with @dlakelan's approach to start things off because this method involves switching things and my method involves learning linux networking commands, and I do not even know where to begin with those - there is no definitive guide on constructing anything like this, it is reserved for the knowledgeable few and seems as though people would like to have it kept that way. We are out to change that. If anyone can point out resources for us to use this topic can serve as a stepping stone for linux networking, the first of its kind.