Limbo really is something else.
I'm no expert on it, but I think pretty much everything works differently in Limbo.
Gravity exists but is subjective to the visitors' will.
That's the easy part.
Any moment they can get crushed by a flaming ball of ice shard tornado of primordial energy soup nonsense metal rainbow vapor.
Unless they manage to stabilize a sphere of limbo, which according to the DMG is a Wisdom DC5 +5 for each additional 10ft or something.
Limbo's randomness make it unique and certainly interesting, but also insanely dangerous and difficult to actually explore.
To me, being in raw Limbo is not unlike rolling on a wild magic table every second, although I'm sure there are more practical ways to run something there gameplay-wise.
You could dump the PCs in a Gith city (or just outside), this way they don't just get swallowed by the raw swirling chaos of Limbo. Cities do exist, stabilized pockets maintained by Anarchs, who exert an unimaginable amount of willpower over the pure chaos. MM says an Anarch has a wisdom of 20, but the willpower they exert over their surroundings is way beyond that. A PC with a wisdom of 20 (+5) would still need to roll a 15 to create a simple 40' bubble, let alone a city, so Anarchs making miles of complicated structures definitely have some unique lore ability thing specific to them. That's a pretty small bubble for an adventure.
(Comment on the monster manual: An Anarch is literally the antithesis of raw chaos, not that I'duse alignment much, but if there's any entry in the MM that should be Lawful it's the Anarch, anyway)
I don't want to discourage you from running in Limbo, quite the opposite.
In fact, I think it's a very (maybe the most) fascinating place and it can be a great medium for epic storytelling that's been (imho) underused by TSR and WOTC, etc.
What makes it an interesting place, the weird, random and unpredictable also make it intimidating and a challenge to use.
In a traditional adventure, there likely was a time of somewhat "stable" statu quo, that the BBEG then disrupts, creating a background tension to your world.
As in, you inject just enough chaos into the world to set things in motion.
Limbo is kinda the other way around, its natural state is raw chaos. You need to inject order, just to exist there.
Now... one thing is you could use pretty much any frontier town from any adventure out there and just plop it down in Limbo. Rename and rework a few things to make it live in its own bubble.
The adventure itself would be much easier if it was constrained into that bubble, maybe with short bouts in the raw Limbo, instead of navigating an endless maelstrom of randomness for the whole adventure.
Limbo would be a great place for a maze too, one that's ever shifting.
Or maybe the PC is an Anarch and they eventually learn to use their power to create a stronghold for the party or a prison for the biggerBBEG. But then they're kinda stuck there otherwise it all ceases to exist.
Limbo has existed for a long while, I'm sure someone already created something much more helpful than that tiny section in the DMG.
Definitely following this thread and I wish you the best success in that.