It is called an ECHOSONIC pickup in three different configurations. TheEPT-1 is a transducer pickup that sticks to wherever you decide is the best sound. I have seen them on guitars, banjos, mandolins, ukes, autoharps, and upright basses. They are quite versatile and not expensive. I know where you can get them less than MSRP.
There are also soundhole mic’s that are easy to move from one instrument to another. I have the iRig Acoustic Stage soundhole mic. It comes with a preamp that clips to your belt or strap. It has volume and feedback controls, settings for steel or nylon, warm or bright.
I have a Myers Grip which works well and is quite portable and small. It's easy to move from one uke to another. It also works well on my classical guitars. https://www.myerspickups.com/
I have a Myers Grip which works well and is quite portable and small. It's easy to move from one uke to another. It also works well on my classical guitars. https://www.myerspickups.com/