One of the areas of Linux that I slunk away from defeated is understanding grub and the boot process in general for Linux. Either I am stopid or it is stopidly complex or both.
Nah, I never understood it. You'd probably be better off writing your own from scratch that does exactly what you want it to do. I've written both MBR and EFI bootloaders, but for MBR it's probably better to copy at least some of the very early boot stuff from somewhere else.
This.. For a moderate somewhat prosumerish user like me, it's these kind of stuff which is why can't have nice things. It used to be the ./configure, make, make install hell which modern package managers and distributions seem to have fixed for most software, now it's this.
Grub is just unnecessarily complicated. Simpler options exist (even ones with the same level of flexibility, though I am most familiar with embedded options there: Something like barebox shows an alternative approach that could be applied to desktop: basically just make a shell environment in your bootloader to script your more complex requirements). But 90% of users nowadays can just use systemd-boot.
barebox can be compiled as EFI payload and used on Desktop systems. The main impediment is packaging it for the OS and scripting the hooks that would write e.g. bootloader spec files on kernel updates.