It's a 1st level game, so we don't really need a way in.
Well, I mean, I meant it as a way in for everybody else - to explain how this seemingly disconnected world of Mega-Mountain is somehow swarming with people already. But it sounds like the consensus is that everyone but me hates airships, so I suppose the idea is nixed.
I totally agree though that we are taking the pendulum too far the other way, especially for the first few low-level adventures. This is dipping into extra-planar stuff, which isn't something anyone identified on the Must Have/Do Not lists. It just sounds like trying to take the thing into "failed Novelist" territory, and that stuff is cooler to look at from the outside than it will be to play in. Players want tangible concepts they can grasp while on the ground, and I think there are far simpler ways to communicate soft barriers to the areas of play than "extra-dimensional reality which only show up in the Prime Material on a blood moon" or wherever this is headed. Needs to be more grounded, is the crux of what I'm getting at.
Allow me to defend the Conglomerate for a bit though, if not as a sort of evil corporation then as a obvious human(oid) antagonist.
First, we wanted a looming threat and a ticking clock - well, while rival adventuring parties are good for putting that stuff into small spaces like dungeons, the Conglomerate is basically the rival adventuring party extrapolated onto a large scale. There is method in their evil - unlike the East India Trading Company, they aren't doing this for profits; this is apparent at all the dig sites they are setting up. The Conglomerate is obviously looking for something and the players will instinctively know (because the Conglomerate are doing it in an evil way) that when they find what they're looking for, shit is going to hit the fan. Looming threat established in an easy-to-understand, minimal exposition way.
Second, we get emergent faction play from their presence too - they are a big enemy, and big enemies unite factions and spawn resistance movements. The Conglomerate's arrival is the core of the power struggle in the area. The raison-d'etre for a few factions, and for unusual alliances, and for betrayals, and exotic mercenary groups, and secret operations... there's just a lot of chaos that something like the Conglomerate causes, and it's great for a mini-sandbox because it allows DMs to generate a TON of NPCs, character motivations, adventure sites, and side-quests. There will be lots of potential for side-missions to slow the Conglomerate down (ambush supply routes, free slaves, assassinate overseers, steal their maps, drive them out of dig sites, etc.), which sets back the ticking clock (something key to Ticking Clock campaigns is the agency for players to buy themselves more time). And it has potential to bring characters to new places, just by virtue of "The Conglomerate is up to something out there".
Third, the Conglomerate provides real-time advancement for changes in the world (which we've identified as something we all want). Players fail a mission? Well, now the slavers are stronger and move to enslave a friendly settlement, or have better gear next time, or they've allowed the Conglomerate to get closer to finding The Big Bad Thing. A key NPC is killed in a slavery raid. A resistance cell is captured and executed. An unguarded vault is locked down. Players beat a mission? Now they've freed an area of Conglomerate patrols, or endeared themselves to a particularly stubborn faction, or made their fights against Conglomerate guards easier. The frogmen village re-opens its doors. A huge beast no longer fears to patrol the skies. A mass exodus of freed slaves migrates across the area. And so on. It's like the Chaos Index in a few products - we can track changes to the region and spawn events based off how well the players thwart/are thwarted by the Conglomerate.
Four, because they are made up of individuals, members of the Conglomerate have potential to be bargained with, reasoned with, turncoat double-agent infiltration stuff. Alpha Squad hates Bravo Squad, so maybe the party dresses up as Bravo Squad and attacks them to get them to wipe each other out. Or maybe if they wipe out Bravo Squad, Alpha Squad is willing to negotiate for the release of an important slave, or turn a blind eye to the party entering a dig site, or give the party a bit of info on Charlie Squad, etc. My point is that there's room for two sides of faction play here: with the groups outside of the Conglomerate, and with the groups inside.
Anywhoo, if not the Conglomerate (and we can re-think the name, if that's the problem; "Empire of the Setting Sun", " Grand Confederation", " or some ironic name like "Hands of the Free People"), then we should at least consider the idea of the big bad faction that everyone rallies against, because it's so insanely versatile yet easy for player's to grasp.