You can giggle as much as you want but none of the golems i posted took more than 3 days to sell. Never, ever. OP made a quite good point on farming ore, as GIO sells higher than BfA ore, and it is much easier to farm. Suggestions that OP made are for everyone and not just for your realm ( where apparently old world enchanting mats cost way more than they should, taking into account how low the margin is). Making gold is not about being lucky to snipe something or to get something to drop, but to have constant income whatever is going around on your realm.

I’ve been trying out engineering with a character I boosted from 70 to 100. When making stuff to sell on the AH as an Engineer, how do you do it efficiently? I’ve been told gathering the parts on your own takes too much time (like mining all the ores you need), but I don’t have an influx of gold to buy whatever I want off of the AH (example being Living Steel. Wanted to make one for myself until I saw how ridiculous the process to make them is and how expensive they are)

-Gameplay- Gameplay has largely been stripped down to be a shell of its former self. This trimming has been going on for several expansions, but now it's even worse. Classes only have so many buttons which has resulted in very little skill involved in PvE (even PvP is a faceroll for most melee, lacking any sort of depth and decision-making as it's pretty clear what buttons to press in any given situation) and it's become more of a gear check. This expansion gave zero new abilities to classes, only took them away.
There's a few profession crafted pets in BfA on the horizon - Battle for Azeroth Tailoring is getting a Hot Air Balloon style pet, and BfA Alchemy looks to be getting a brand new Transmute Meat to Pet. There are some mount buff consumables from both BfA Leatherworking in the form of a mount barding, and Blacksmithing in Battle for Azeroth will be able to craft Stirrups and Hoofplates to increase mount speed and allow you to interact with things while mounted.
I think that's server dependant. I make a lot of Golems, but the price on my server is high enough that you could buy all the living steel and still make about 20K (almost 200kg on AH). Its just that you proc all the way up the chain. You proc 20% of your trillium, and then 20% of your living steel. SoH and Ghost Iron are such low effort farms, too. 20% of 180 Trillium Bars at 500g is 18k more profit, 20% of 150 Living Steel at 3500g is another 105kg. That's an extra 25k profit per Golem. If they stop selling stockpile them for the next expansion, they always boom with the price of herbs. And a consistent 20% proc rate is the opposite of RNG, its extra free stuff as a benefit to completing an extra quest (not to mention for new alchemists the investment of leveling Vanilla Alchemy). You're looking for some get rich quick scheme, where the real way to build wealth is patience and volume. No market is going to be viable because you want it to be. Only because you make it viable.