This is true for "regular" Gsync, but Gsync Ultimate goes all the way down to 1HZ. Any dip below 30HZ is still covered.Freesync is the same as Gsync when it comes to sync rates and has been for a
very long time now (it's no longer 2016). You can find Freesync monitors that support rates as low as 30Hz. It just depends on how good the panel is and the price of the monitor.
Here are a few quick examples I found in a few minutes on google:
AOC AGON AG352QCX