I have a 16 port 10 gbit Ubiquiti switch, and it has fans. But they only ever spin up when I (re)boot the device.

To my knowledge all their switches are fan cooled.

Thank you. Any direct impression on how noisy they are?

I don't really know how to answer that. I ususally put them in (small) server rooms. When they boot they're a lot more noisier than normal operating. The poe versions do make more noise than the non-poe.

I have the 24 port poe model and swapped the fan for a noctua. The stock fan wasn't noisy by rackmount switch standards but it was more than I prefer to have audible in my living space.