Typing the domain in there has the side effect to submit the domain, if has not been done yet.
It should be safe, as the domain will be discarded if the preload attribute is not set on the HSTS header. However, I felt like it was worth the mention since @Svavar_Kjarrval was asking about a way to check the status specifically. As far as I know, such feature doesn’t exist (there is no way to know if the domain is waiting to be approved vs not submitted).