2 post lifts are the best option for working on cars.
4 post lifts are ok for servicing work, but you’ll struggle to do anything major like remove a gearbox.
And you’d be as well working on the floor than over a pit with a car. Only things you really do with the car fully up in the air, is drain the oil.
A 2 poster that only goes up a few feet will be of far more use over a solid floor, than having a pit that will inevitably just get in the way. And to meet modern regulations, the pit should be long enough that you can exit it at either end when a vehicle is parked over it, however that’s for a commercial workshop.
Fumes are a risk with a pit, however as long as there’s air movement in the workshop, and you’re not doing something stupid like spilling petrol in it, the risk is very minimal. But you really do want it fully lined. Modern pits are nearly always done using prefabricated inserts, as it’s the most reliable method. Dig a hole, position insert, pour concrete around it, job done.