Pretending until you make it is fine for confidence. Never for credentials.

Acting more sure than you feel is reasonable, since confidence often arrives after the behaviour rather than before it. Claiming skills you do not have is a different act with a different way of failing. One gets you through the door of something you can learn. The other puts somebody in a position of depending on an ability that is not there.

Keep the pretending on the outside: posture, tone, walking in like you belong. Be exact about what you can do. I have not done that yet and I can learn it fast is the honest version of the same energy.