I never thought that something like a GPS wall clock even existed!
People don't bring hanging clocks, so why...?
However, I read a magazine article on it the other day to satisfy my curiosity. It actually made sense.
There are times when it doesn't receive a signal due to being placed in a location away from windows inside buildings, but
The GPS clock has a 5x signal receipt strength, and can get a signal from almost anywhere in buildings.
A certain large Japanese company bought 260 GPS clocks and receives signals from all over their building.
It's being sold as the SEIKO Space Link GPS wall clock. It's not only a wall clock; it also receives signals from locations all over the world.
It sells for about 200 USD in Japan.
It's cheaper than I expected.
Reference. Pen PlusThe Clock Book CCC mediahouse Aug 29 2015 page24-25