

It’s literally super common. Google’s GBoard has it, but the first app I know about it was the now discontinued Swype app. There was a big commercial for it in 2010 for the Samsung Galaxy S about setting the guinness world record for fastest text https://www.windowscentral.com/samsung-and-swype-helps-set-world-record
We’re basically at least 50 different countries. It depends on which sub-country you’re in to know how strict the regulations are. However, what is illegal on paper is very different from what is often enforced.