Find your tribe in a Sea of Creativity
The current discussion about "a big advantage for the yeerks is that no one knows there's an alien invasion" reminds me of your ficlet that became the first chapter of All Assorted Animorphs AUs; Elfangor meets the team as adults, and they *do* go public about the invasion. It ends poorly. Sorry kids, no clean option here.
The yeerks' need for secrecy and the Animorphs' need for secrecy are not the same, in a really interesting way.
The yeerks need to keep humans as a whole from knowing that mind-controlling alien invaders exist. This means suppressing all knowledge of extraterrestrial everything, even when it means covering up for their enemies.
The Animorphs need to avoid controllers knowing who they are, and don't have a reliable way to know which humans are controllers. This means they have to protect their names and faces at all costs, but would prefer it if humanity did know the yeerks exist.
Like, look at #22 where the controller-cops indirectly protect Jake by inventing reasons a tiger could be unconscious on the floor of a California mall. Or the times the kids win victories over controllers by getting them to act alien in front of civilians (e.g. #12, #35). The yeerks are the ones who have to keep the entire war secret.
By contrast, the kids just have to keep themselves secret. Look at the number of times they straight-up admit they're morphers and not real animals. Sometimes it's around people too remote to be controllers, like Derek (#25) and Yami (#44). Sometimes it's a civilian who just reacted with shock instead of anger to the sight of morphing (e.g. the home cook in #5, the busboy in #35). Sometimes it's even a known controller, just as long as they don't give their names (e.g. the opening of #18, Visser One in #30). They don't even go out of their way to actively maintain the fiction they're andalites — they don't dispel that belief if they can help it, because it's useful, but they're not going to spend a ton of time and energy on it. Just as long as no controllers know that Jake Berenson of 123 Street Road, Townsville, CA, can morph, it doesn't matter what else leaks.