Once I had to transfer fish from a place like ~200 km from my pond.
I placed a large plastic bowl in the car and a garbage bag inside it. After that I filled it with water and added my fish.
They survived the journey because of the aerator that provided enough oxygen. It was the usual aerator, powered by car charger.
The fishkeeper gave me advice how to make it even more simple. He said that I needed such bowl ONLY partly filled with water. The fish wouldn't be able to dive in and in a result they would splash water a lot. As far as I understand, they get enough oxygen to live.
Since I had everything prepared, I used the aerating method but in case you aren't able to provide such service, the second advice might be useful.
(Do it on your own risk and don't blame me
).
