Hot take but I think New Vegas' overarching narrative post guy who shot you in the head is overrated at best, lib at its worst. Caesar's Legion is the worst written faction in the game and is basically your Bethesda edgy faction that you can pick for your "evil" play through (yeah I went there).

NCR is the best written faction in the game but the problem is that (probably due to the 18 month development cycle) they don't actually have any real opponents besides edgy skirt boys who enslave women and a geriatric computer screen with mega death robots.

If the people at Obsidian truly wanted to write a compelling anti-imperialist work they would have never written Mr. House and Caesar they way they did. If a work doesn't have communism as its answer to fascism then the work itself is fascist (liberalism is just the moderate wing of fascism). The easy fix for this would to not give the geriatric elon musk a mega death army of super robots and instead actually have him strategize and pit the two major factions against each other. Then whatever choices you made in his questline would be more meaningful than cleaning up trash since he would actually have a stake in them. Like stories need to have tension in them.

Caeser's legion is the dumb. Completely scrap that idea. No, having a purely "eeeevillll" faction in your post-post apocalypse sci-fi is a liberal power fantasy about "hooman-nature."

Just make the faction that competes with the NCR a result of blowback from their war crimes and corruption, that's literally all you have to do. Just make the story that the NCR bullied and oppressed ethnic minorities in Nevada (this is in the base game as well) and so they all banded together (a la, putting aside cultural differences and adopting 1 banner sorta like the legion) and sought help from a neighboring superpower in Arizona/New Mexico and Mr. House. Then you can write conflict about unresolved tensions within the united tribes or tension between their backers (regional superpower from abroad or Mr. House's ulterior motives). They feel trapped because they need the support in order to do intifada and push the NCR out completely so the player character has to resolve these tensions but since they are fighting for the underdog they wouldn't be as materially supported as they would be in the NCR + having to deal with NCR rangers trying to kill them all game.

You choose the liberal democracy NCR as the "bad/lazy" option where you have to pick up their slack for them (and also do some fun ethnic cleansing). The exchange is that you materially benefit from the NCR's projected power and resources in the region (making the game easier in a brutal way), but not much else while they do imperialism and try to replicate amerikkka and the game would force you to confront the consequences of the NCR and implicate you in their crimes.