iPhone thinks my timer is a headphone

I recently purchased an external hardware timer that connects to my iPhone using a USB-C adapter. The problem is that, when I plug it in, VoiceOver immediately goes silent. With sighted assistance, I've determined that iOS is asking me whether the device is a headphone or another device, and we have selected other device. Still, no VoiceOver output, as if all sounds are being routed through the USB-C and into this device that has no way to play sounds.

I've poked around in Sounds & Haptics. Under headphone safety, I can tell iOS to forget all USB devices. But that's no help. What I would expect is a list of USB devices and the ability to specify whether they're headphones or not, but I've been unable to find such a list.

Alternatively, is there a way to direct VoiceOver to always send its output over the built-in speaker rather than through the USB port?

Bonus: I actually do have a wired headset that I sometimes use with this iPhone, and when I'm using those, I really do want VoiceOver to go over USB-C to the headphones. But VoiceOver should not try to play sounds and speech through my hardware timer.

Any help would be appreciated. Thanks.