Alright, here's a summary of my final moments with Fallout.
I went to Adytum to fix their hydroponics, get hardened PA and a Turbo Plasma Rifle, and liberate them from the corrupt Regulators with the help of the Blades (went well, only a few generic NPCs died in the attack). I then traveled to the Followers base to recruit Katja and get their assistance in assaulting the Cathedral.
What transpired was a total clusterfuck. After getting info from the informant, I went upstairs with my full party and several FOA troops only to be ambushed by Nightkin with plasma & laser rifles. I kept reloading as I didn't want my companions to die, and navigating was a total pain in the ass thanks to everyone blocking me. I eventually killed Morpheus and gained access to the basement, and I died over 5 times trying to kill the mutants guarding the Vault entrance (a mixture of them being oddly durable and them getting lucky with critical hits). Save scumming ensued as I fought over 8 mutants on the third floor (blame the lucky mutants and my companions being fragile), but I was able to show the Master the error of his ways thanks to the holotape I got from Vree.
I went to Mariposa at the behest of Elder Maxson, and returned to report my findings. After deliberation with the High Elders, they deigned to give me a whopping three Paladins to assault Mariposa (only the outside, of course). Mariposa was another clusterfuck, but not because of the mutants (they were pushovers compared to the ones at the Cathedral), but rather due to all the goddamn laser barriers that kept damaging my companions. I soldiered on until I was offered to talk to Lou, and I listened to as much of the late Tony Jay's dialogue as I could before I killed him (a critical shot to the eye with the Alien Blaster, which caused Lou to fucking implode in on himself). After activating the self-destruct sequence, I endured the barriers as I escaped, but Dogmeat died to one of them (I kept reloading the save, but I eventually got tired and said fuck it).
As thanks for my service to Vault 13, the Overseer told me to fuck off. Got good endings for everywhere except Adytum and The Hub.
Overall, the final portions of the game felt like a tedious slog with companions.