I think you’re right! I fixed most of my issues with the wakeups using the following rules that I put in the /dev/rules.d/ folder:
/etc/udev/rules.d/20-suspend-fixes.rules
ACTION=="add", SUBSYSTEM=="acpi", DRIVERS=="button", ATTRS{hid}=="PNP0C0D", ATTR{power/wakeup}="disabled"
ACTION=="add", SUBSYSTEM=="serio", DRIVERS=="atkbd", ATTR{power/wakeup}="disabled
The second line disables the keyboard from waking the PC, which fixes the lid waking the machine (along with the first line) AND the AC being plugged in (which sends a keyboard wakeup as well). You lose the keyboard wake-ups but the touchpad and everything else work fine.
I noticed you linked to your GitHub. Is there a guide for consumers to customize and flash their own EC? I haven’t done the research yet.