The idiom "on board" may be used to imply involvement in a project or organization, or working for a company. E.g.
Welcome to the team. It’s great/nice/good to have you on board.
What are some common ways to convey its meaning in this context other than
Bienvenue dans l'équipe. C'est super de vous avoir avec nous.
I think the literal translation à bord is not idiomatic (in this context).