I bought a penis head pump which has exactly the same mechanism/hose etc. It broke very quickly after use, also the seal didn’t hold the pressure well. Needed to keep pumping to maintain an even pressure.
Later I purchased the quality velseal cylinder with a seperate brass brake bleeding kit (the pump) for more reliable (full penis) pumping.
The difference was a far more repliable, and superior pump, that actually does the job right.
So as far as the cheaper pumps go, stay away from them! It will cost you more in the end to replace them when they break!
The more advanced pumps also allow you to detatch the hose whilst maintaining pressure, which is helpful.