"no speaker" can't be correct considering the startup beep 
Depending on the wiring that one could potentially even be misused as a (very low-quality) microphone. Aside from that the GPIO Pins (https://www.raspberrypi.org/documentation/usage/gpio/) can (probably) be used for input if you add PWM between them and the Mic.
@robolink_leila No worries, as mentioned it was large enough to be cut in half
I also only received one piece of dual-lock, but it was large enough to be cut in half...
I didn't manage to test this in a second attempt since now neither zumidashboard.ai nor zumi1234.local are loading at all... But either way, I don't want to have to reconnect Zumi every time, how can I set it up to always directly connect to my home WLAN? And/or is there any way to use the USB connection to troubleshoot the system, SSH onto the RPi?
Thanks, I managed to use my phone to have Zümi connect to my home WLAN and then access zumi1234.local from my PC (including SSH access), but it seems the connection was lost the moment my phone disconnected from Zumi's network, is that correct? Can that be changed or troubleshot then? Obviously I don't want to have to use my phone as mediator every time...
My PC doesn't have any WiFi hardware. How can I configure Zumi to connect to my home WLAN then?