Even the vax is not a guarantee. I've heard of people not being able to get to their home countries even with the vax and having multiple negative tests. Some people have been stranded outside of their home countries for over a year now. Especially if they come from a place with heavy lockdowns and border closures. If you travel abroad you have to be prepared for the possibility of being stranded wherever you travel AND getting the jab.
I know Australia is doing that but I hadn't heard of any other countries with those policies.