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.
Now this is dull lol. This is def something I’d do too if it bothered me enough.
It took a few decades of thinking about it before I finally acted on it.