Thanks, but I had seen that a few times before. The step I was missing was to reproduce the project it was forked from, but replace the contents. I remember from a while back that someone posted some step by step to get it to build correctly in the lede source/package/kernel path when you build lede using make menuconfig, but maybe I'm making that up.
I guess if I spent a few minutes more thinking about it, I may have figured it out sooner. The gpio-irq sources are missing the structure to get Lede to incorporate and allow for a quick build. I've forked the gpio-irq sources and modified it with the correct makefile structure in an attempt to make this easier to do (I think).
Anyway, you can find my fork here.
cd source/package/kernel git clone firstname.lastname@example.org:buelowp/gpio-irq cd ../../ make menuconfig
Find the new module in Kernel Modules and then Other Modules
Select it as a module (M)
exit saving .config
You'll can find it in build_dir/target-mipsel_24kc_musl/linux-ramips_mt76x8/gpio-irq