Can we use an external web camera on a smart phone(android or iPhone)?

As a subject shows.

I will try using an external web camera, attaching to android or iphone mobile devices,

but I found a topic that zoom dose not recommend an external web camera on the smart phone.

Is it a truth?

reference:

https://zoom-support.nissho-ele.co.jp/hc/ja/articles/360029790532-%E3%82%B9%E3%83%9E%E3%83%9B%E3%81%AB%E5%A4%96%E4%BB%98%E3%81%91%E3%82%AB%E3%83%A1%E3%83%A9%E3%82%92%E6%8E%A5%E7%B6%9A%E3%81%97-Zoom%E3%83%9F%E3%83%BC%E3%83%86%E3%82%A3%E3%83%B3%E3%82%B0%E3%81%AB%E5%8F%82%E5%8A%A0%E3%81%99%E3%82%8B%E3%81%93%E3%81%A8%E3%81%8C%E3%81%A7%E3%81%8D%E3%81%BE%E3%81%99%E3%81%8B-