I actually read the question as thoroughly as I could. 3 times. And I get more confused for each read.

You spend time describing your setup. But what is your actual root issue? Why do you insist on doing it in this way? Why do you interpret the bug report like this? (I intepret it differently). The documentation is actually not that bad but I do agree that it should be much better in some crucial key places. But we seem to be chasing a different rabbit.

I do not run Gentoo so the "OS Specs" is alien to me. There are many ways to boot a system but you seem to be quite far a long so we do not need to dive too deep there.

But FreeBSD is in the transition phase of moving from a loader based on Forth to one based on Lua. FreeBSD has been using the Forth loader for many years so many will reference it. The Lua loader was introduced in 11 and made default in 12. See LUA loader on by default

And again because it has been used for so long some Forthism has crept into /boot/loader.rc.local. This is what Kyle Evans and Warner Losh tries to explain further down in the bug report you reference.

On a modern FreeBSD system you should not tamper with /boot/loader.rc.local. It is there for legacy reasons. it will only be read by the Forth loader and not the Lua loader.

I want my Forth!

If I understand correctly you build everything from source including FreeBSD itself. In that case you can edit /etc/src.conf and set:

WITH_FORTH="yes" WITHOUT_LUA="yes" 

This then choose what loader you use.

The modern way

The proper way to change loader settings for years have been using loader.conf(5). This file is read and parsed by both loaders.

You just need to connect the dots between your "Half Solution" and Bug 235040

Edit /boot/loader.conf (which is "user defined") and add something along the lines of:

exec="gop set 0" exec="gop set 2" 

/boot/loader.conf.local work the same but is intended for machine specific settings for sites with a common loader.conf

You can write your own Lua scripts as you could Forth but it is not intended for common usage.

Default resolution

You write that your resolution defaults to 1024x768. Rather than using gop set you might be able to use efi_max_resolution (again loader.conf(5)).

Value Resolution 480p 640x480 720p 1280x720 1080p 1920x1080 2160p 3840x2160 4k 3840x2160 5k 5120x2880 WidthxHeight WidthxHeight 

So in /boot/loader.conf you could try:

efi_max_resolution="1080p" 

Nvidia driver

Again it is unclear precisely what problems you have. You state you are using x11/nvidia-driver. This is only relevant for X11. During boot the vt(4) console driver should start. When doing a BIOS boot it will switch to 640x480x16 if you have no KMS driver (like you). With UEFI I would assume it keeps the resolution as it has already switched from textmode to graphics mode.

The driver will then only be used when starting X11. No config should be needed as it should be autodetected. This should either send you into a graphical login manager like Slim or directly to the desktop.

Switching between RELEASE and STABLE

If you want to live a little more frisky lifestyle then your can switch to STABLE. Or go completely wild with CURRENT. But if I have understood your issue then it would not make any difference.

24.4. Tracking a Development Branch

What's the difference between the three FreeBSD versions? (Current, Release and Stable)