To combat this, I recommend having headphones (any pair cheap in-ear headphones without a microphone will do) for each guest so that they can hear themselves while recording, and will then be aware when the microphone strays from their mouth.
Great quality, low price. They come with both a USB to micro-USB cable, an XLR cable, and a wind screen. Use the XLR cable to connect the microphone to the Zoom H6. The only potential issue with this type of mic is that it is a handheld microphone, and oftentimes people move their hands a lot when they talk, subsequently moving the microphone away from their mouth. To combat this, I recommend having headphones (any pair cheap in-ear headphones without a microphone will do) for each guest so that they can hear themselves while recording, and will then be aware when the microphone strays from their mouth. Be prepared to have to signal your guests to move the microphone back in front of their mouths.