MS Teams publish App for specific user

Hi Team,
we require some clarification regarding the integration of MS Teams. If we upload the bot Manifest zip file in the Teams admin portal, will it be visible to all users or only to a specific group of users within the organization? Our intended use case is that it should only be accessible to the people involved in setting it up, not to all users of the organization.
Also is there any limitation in MS teams (Like Button character limitation. QR, What type of button will support)
CC: @Agilan_KS @Hitesh