Everyone understands the vast amount of information we must learn and known one expects you to know it all. Don't interview for a job looking for an expert at something you know the basics about.
I think imposter syndrome comes feeling insecure about not fully understanding things. The only way you can be an imposter is to act like one. People will respect you for saying, I'm not sure, let me go look into that.
Our job isn't to know everything. It is to a be a badass at quickly figuring things out. Focus on learning how to quickly find answers and solve problems and not being a master at everything.
It has taking me decades of mastering everything to realize how much time I wasted. I hire people half my age now who can do as good of a job as I can. Some of them are afraid and can't seem to get things done. They feel in over their head and shut down.
Other people come in and they know a few things but, don't understand others. The are confident they can learn everything and don't freak out. They quickly become ninjas in many areas simply because they aren't afraid and not trying to fake it.
After interviewing well over 100 Devops recruits I can tell what type of person they are 90% of the time in interviews. I don't look for an expert at one thing. I look for people with some experience with some tech we use. People who can stay at a job more than 2 years and, people who have shown they can master a few complex systems.