When I create a Firebase service account for the admin SDK, I retrieve credentials that include the service account name and private key to authenticate.
I'm managing the private key as a "secret" environment variable in my build tool, i.e. it won't be exposed to other users of the build tool.
Is it advised to also maintain the service account name as a secret or is it safe to expose it to other developers? I'm kind of comparing it to accessing an email account, where the email address is publicly known (compare: account name), but the password to the account stays secret (compare: private key), but I may be wrong here.
No, there is no need to worry about that name of the service account that you use. It's just the key that is used to help you identify the credentials, and has no meaning in securing those credentials.
If someone would be able to retrieve your full credentials based on the service account name, I'd say the problem is much bigger than just those credentials.