Hi ReDriven and welcome to the forum!
I don't own a Sierra so I can't really help you much, other than suggest you use the search function up top to search your desired Sierra model and engine types for finding bits of info that you need or are interested in. From what I've seen, a lot has been asked before (multiple times) without any feedback or contribution afterwards for better fixes etc etc, so some of the resident members here might not respond until some homework is put in or something more specific is brought up. From there if you have any further questions on something and want more detail, the guys that know more might be inclined to give some input.
I've watched a few of your videos in the past whenever they come across my feed including I think one on the Grand Vitara (NGV) before finally pulling the trigger and getting one. It's interesting that you've decided to make a video on the Sierras because those vehicles are getting quite old now. Great little machine, but a bit too much work for me in my time poor stage of life.. My missus probably needs more tech/luxury comforts than it has also.
Heh, I have good memories of them as a child. Used to go up the ranges out of Brisbane on 3-4day trips in our little 4wd group at the time through the mid to late 90s. Me and my dad in his 80-series, uncle and aunt in a hilux along with 3 others - a Maverick I think? (it's been a long while now..), Graham in a Paj, and Marko in his little white Sierra.
The adults would always take the piss on Marko never being able to keep up the speed on the highway, but the positions usually turned when it came to the hard parts on the tracks. There was a time he allowed me to ride shotgun for a bit and I don't remember much other than it being really bouncy, and REALLY fun. </nostalgia>
Can't wait to see what video you make up with your research here!