In Bear for Mac, you can easily open notes in their own windows: Double click on a note in the Notes List or select Note → Open In New Window from the menu bar.

You can open note links in external windows by holding the ⌘ key while clicking the link in Bear’s note editor.

You can also make the window float on top of all other windows on your Mac. Once a note is floating in its own window, you can select Window → Float on Top. Alternatively, simply click the more (⫶) menu, then click Float on Top.