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.
I simply hang those nearly empty bottles upside down and let the remains drip into the new bottle.
Compared with that your solution is high tech.
I put a bit of water in to and shake it so it comes out easy.
That’s what I’ve been doing for the previous 45 years or so.
What did you do before that?
Probably asked my mom.