I’m not sure what level of security you’re looking for. If you just want most users to not be able to see something, and aren’t that concerned if someone with skills breaks through, then approaches where you hide things on a page are OK. Even though something on a page is “hidden”, my understanding is that Bubble still loads it, so someone with technical skills could see it.
However, if you need to protect data, then you need to do so in the privacy rules. Protecting Data - Bubble Docs This stops Bubble from sending the data to the page (and also from users searching your database without permission). Since you have only 1 password – I think you’ll need to set up a single “user” that has a login and password, and everyone uses that.
Another option is applying a password to the app in the Settings tab. This will apply to the entire website however.