Can Samsung watch4 be used without connecting to a mobile phone?

Can't use it. As you can see in official website, Samsung made it clear that all the watches in the GalaxyWatch4 series do not support the ios system at all, so all Apple devices cannot connect Samsung Galaxy Watch 4 (40 mm, 44mm) and Watch4Classic(42mm, 46mm).

Samsung watch4classic can't use WeChat independently without connecting to a mobile phone. At the time of research and development, Samsung watch4classic did not set up the function of using WeChat independently, and it must be connected to a mobile phone to use it. Therefore, Samsung watch4classic cannot use WeChat independently without connecting a mobile phone.

Samsung Watch4 supports the built-in GPS function, so it can record sports data such as kilometers and running distance even without connecting a mobile phone. However, please note that if you want to use other applications or receive notifications, you need to connect Watch4 to your mobile phone.