@Lioncour,
All portable Bluetooth speakers are open if a password to connect isn't being used.
Quote:The speaker should open up for the next user automatically or with the press of a button.
You need to think about software here. Each new person using the speaker can step on the past one and play their own music before the present playing song before it ends and play their music right then.
Think of using Spotify where many users can add to an ongoing playlist.
If this is a business where you considering this idea... please note that someone might play something unsavory (explicit lyrics, whatever).