UNO FCC certification

Yes it is reported that it does have FCC compliance. The reason you can't find it on the FCC web site is that they only list the devices that are intentional emitters. These need an FCC identification number and that is what you are looking up on the site. However there is no need for an ID number for devices that are not intentional emitters, like the Arduino.
If you want confirmation of certification then contact the manufacturers or your suppler.