Lots of great comments! About the Hellcats, the reason I am doubtful that the mercenary faction is a remnant of the pre-war military is because the only mention of prewar "hellcats" comes from the news presenter on the TV during the intro to Fallout 4. From him we learn that the 5th Infantry is fighting the communists on the island of Mambajao in the Bohol Sea (this is part of the Philippines). During the presentation he describes them as "mechanized hellcats".

There are a few problems with the idea that the 5th Infantry became the Hellcat mercenaries, or that even before the war the Hellcat power armor existed.

First, they were in the Philippines when the bombs dropped. This news broadcast was from the very morning the bombs dropped. So they weren't in Appalachia. Sure, it's possible that some or all of the 5th Infantry found their way back to America 20 years after the bombs dropped, but it's unlikely due to the pacific ocean being in the way.

Second, "mechanized hellcats" doesn't imply a unique suit of power armor, because all infantry was mechanized by that point (so of course the 5th Infantry would also be mechanized), and "hellcats" isn't capitalized in the news prompter's subtitles. This implies that "hellcat" was a nickname given to the 5th Infantry, much like "hellcat" was a nickname given to the 12th Armored Division during WW2 in our own universe.

And finally, every pre-war suit of power armor has a paper trail--terminals, holotapes, even loading screens--explaining their existence in the universe. It's highly unlikely that the developers of Fallout 4 would have envisioned another suit of power armor just for one infantry company to use in the Philippines (and no where else?), and not have created a paper trail of lore for it.

That said, it's entirely possibly that the developers of Fallout 76 could have missed all of this context.

I honestly love how power armor was represented in 4 and 76 the only criticism I have is that fusion cores should last longer in the suits since they can power settlements for years in game without failing

I really like the idea of companies making power armor suits for industrial reasons, it fits with how in the real world advancements originally used for military purposes eventually end up released to the public in more domestic circumstances. It's also sort of an inversion to what happens in the Titanfall series, where the AI Titan mechs were originally based on modified tech used in advanced suits used for farming and terraforming

Sorta wild how the Chinese couldn't figure out Power Armour, but they could figure out invisibility. The US and China dipped into eachothers technological pools, but never as good as the others own technological specialty. The Ying and Yang.

In an alternate universe, after 1:10. The resource wars ended and everyone got along.

Hey Ox, wanted to mention as a recent sub that I have been using the literal years of information you have to make the best of a series of survival mode runs. Your location break downs are phenomenal.

The TV news broadcaster in Fallout 4 mentions "Mechanized Hellcats" meaning that the Hellcat Company IS a Pre-War military unit and that means Hellcat Armor IS Pre-War as well.

Slight reminder that the T-60 series is just an overhaul upgrade of the T-45s, think of them like the Patton series of tanks, with the M60 being the final form of them, the T-51 is the M1 Abrams of the Power Armor world in Fallout. while the HellFire is the Abrams X

That grafton steel helmet looks like a nod to the storyteller.

Frank horrigan IS wearing the Vulcan power armour, this was tested in early beta stages and was only used by frank himself

Of everything in the fallout universe, I hope power armor becomes real life more than anything else. Imagine being able to buy a surplus power armor frame.

I think the vault 63 power armor should have been included.  It looks similar to the Chinese stealth suit

Oxhorn, I've watched your videos since I was around child and I've got to say that your lore videos are the best there are when it comes to fallout content. Thanks for making all the videos all these years

In regards to the Captian Cosmos armor, it's worth noting Johnny Morton, an actor we find as a feral ghoul during the Captain Cosmos quest was directly mentioned in season 1 of the Fallout show as a former co-star of Cooper Howard.

So...

I absolutely love the winterized T-51 being practically indestructible in fallout 3 is funny and it just looks so good I even use the winterized coating in fallout 4

The frame is the key to all that POWER!! Its why even after the apocalypse factions can craft their own custom armor. All one needs is just the frame, the outer shell is somewhat easier to make, whether its some junk welded and with tied up bits of car tires and slabs of wood, or something more refined and even machined doesn't matter. I love how this is reflected in FO4.

Damn I love when you post new long form content!

I believe that you forgot the Enclave's Tesla Power Armor(s).

The mention of Canada makes me wonder what a Fallout Canada game would be like. I can already picture the wild life already hardened to cold wild lands being truly scary.

I did not know this so I thought I would include this as a comment, it's nice to learn something new everyday isn't it?
A retcon (short for retroactive continuity) is the act of adding, changing, or ignoring previously established details in a fictional story through later works, often to explain inconsistencies, fix plot holes, or adapt to new ideas. New information is introduced that recontextualizes past events, characters, or settings, essentially rewriting the narrative's history to fit the new additions, according to the Oxford English Dictionary.