Is it possible to create (and save) a fluid app with multiple tabs?
Developer of Fluid here. Although there's no explicit support for this, it can sorta be accomplished by:


Launch your Fluid App and set up the windows and tabs you would like to appear on launch.
Ensure that the following preference is enabled:

Preferences > Behavior > On startup restore windows and tabs from last time
Quit and relaunch your Fluid App, and you'll see the same windows and tabs are open.