This is one of the reasons why I consider FO3, FO4, and obviously FO 76 to be non-cannon. When Bethesda “acquired” Fallout as a whole they didn’t do the og lore and cannon justice; especially the idea of synths. They also didn’t understand fallout was about humanity crawling out of the ashes and rebuilding society. After 200+ years no one in 3 and 4 have cleaned up the trash, rebuilt walls, have more than a few lights on, fixed up and rebuild vehicles or made them into carts, and so on. They don’t feel established they just sort of exist in the world waiting for the PC to do something. In the other games things have happened and are happening without you and it feels like thing will go on in some way even if you do nothing. The brotherhood was a dying faction in FO2 and all but gone in FONV; same goes for the enclave. By now they should have been destroyed, absorbed completely by other factions, and or are simply a relatively small presence changing from what they were to something new with alliances and trade. Although it is possible that the brotherhood could make it further east after FO2 they had dwindling numbers and a lack of resources unlike in 3 and 4.
I try to stick with the og lore and cannon of FO, FO2, and FONV when I can. T60 power armor isn’t canon but I treat is as a version C of the T51. Also the laser musket is a really bad design and I ignore it completely much like the aliens being anything more than a joke. The world isn’t a dust bowl most of it would still be intact. In 1 and 2 the forests and deserts are much like they are today and would be growing back over time. It just seems like the world is a desert because that’s how it actually looks out west. The cities and large towns were hit, but the rest wouldn’t have been priority targets. Also unless the nukes hit the ground like at The Glow they would be no radiation left in most places due to air burst bombs. The biggest danger to other places would be shorts in power causing massive fires and the lack of power forcing most people south toward warmer weather and longer growing seasons (assuming they make it that far without proper survival skills, gear, meds, and food / water). There would be places with working vehicles after the bombs, but busted / congested roads, lack of communication, lack of working gas pumps and batteries for non-nuclear vehicles, and people fighting for scraps after the supplies ran out would hinder travel and vehicle use.
For places not burned by short caused fires the animals, collapsing infrastructure, falling trees, and general damage from wet and poor weather would damage homes. The further you get from target locations for the bombs the more likely you are to run into relatively intact places (baring what time and animals do to it), normal animals, and a lack of most people. In those locations molds and other hazards, weather, animals like bears and mountains lions, brush hidden danger like cliffs, and lack of support are the biggest problems. On the plus side fresh radiation free water (dirty water) would be easier to find without digging wells for clean water, and natural food in the form of tubers and the like along with animals such as deer and fish could be found. Depending on your location you should also be able to find normal cows and such as well. Still running to the deserts, plains, and swamps in the south would still be a necessity at times; especially in the winter for those who can’t survive on their own.
I have my own idea of how NV would end based on a slightly alternate House ending where you as house’s prodigy convince him to help / value freeside. The short story is that the brotherhood still exist in that they have been more or less absorbed by the rangers that broke from the NCR. Together they found and took in the elderly enclave member who helped at the second battle of hoover dam to acquire their knowledge. I’m not sure if I would call them Steel Rangers or something else, but they are still fairly small and take in new members only after strict vetting and tests. They focus mainly on securing the roads and land surrounding New Vegas, with the help of some of House’s Securitrons that are not stationed in and around the strip and freeside. They also no longer hunt down people and forcibly take technology, but they still seek it out and trade for it in some way.