If not gravity then some mechanism to determine the tendency of things to go down. You went on with it anyway without attempting to address the holes. Again, a rock drops because pressure pushes it down from the energy it took to put it up there. The pressure this creates below the rock should send it back up then.
Similarly, if I grab a pinecone from a tree and pull it down near to the ground, it should fly up to the top of the dome.
The pine cone has more density than the atmosphere it is taking up, so it's going to push through the resistance of the atmosphere under it.
You know those party helium balloons with the little weight attached that stand up as the weight touches the table or floor. Pull one of those down and you get the drift.
Denpressure. No gravity required.
What's making the pinecone push through the air beneath it? Its density? Why does density result in a push towards the ground?
To understand it, you have to see it from the ground up.
Take an apple tree. Its seed growns by rain pushing it against the ground. The seed resists this by pushing against that and also stopping itself from being pushed under the ground. It does this by spreading itself out, as in, roots. The more dense it grows , the more it is being pushed and the more it pushes back by levering itself by spreading out. As it does this, in time it balances itself, as in, it het's out the balancing sticks, as in, it grows branches to ensure it pushes through the least resistance, as in as straight up as possible.
As it takes in enery pushed up through it's roots to it's trunk and branches, it starts to create stems, then a small apple. The pressure up this apple is small as the apple starts to push into it. It gradually gets more and more as the apple continues to take in more nutrients and so, it keeps pushing against the pressure as the pressure keeps pushing back and around it. It gets denser and has s skin to allow it to keep it's density whilst not being taken apart.
As it grows, it's stretching the stem. Just like someone hanging on a rope and adding lead in their pockets, kind of thing.
In time, the apple gains a little bit more mass forcing more pressure against it, until the stem can no longer hold that pressure, so it's pushed through the least resistance until the resistance stops it, which is the ground.
Nothing is pulled. There is no such thing as pull. It's all the force of squeeze and push on dense objects/marterial, either down in the case of a more dense material or up in terms of expanded matter as in helium, hydrogen and such like.
No such thing as gravity.