I use shampoo from a large bottle with a pump. The pump can't get the last bit out of the bottle.
I cut apart the pumps from two shampoo bottles and epoxied the caps together to make an adapter. I'm going to use it to attach the old bottle to the new bottle and drain the remainder out.
In use the tube points down into the new bottle.
It does not have a hole, but the tube is pretty wide.
I had thought about providing a way for air to pass into the upper bottle, but I decided it probably isn't necessary.
My expectation is that the shampoo is thick enough to cling to the inside of the tube as it drains down, and thin enough to leave space for air to pass up through the center of the tube.
It's getting it's first use today. I'll leave the old bottle draining into the new one until tomorrow morning, so even if it has to do the glug-glug thing, it should still successfully drain completely.