Can I add apps or devices, monitors to the home page of the app?
I’m new to smartthings - figured this would be a common topic but couldn’t find anything. When I open the app it displays ‘Everything OK’ then shows only my leak sensor and status. I would like to see other things. I would like to be able to selectively add to what I see on the home page. Is this not possible?
Unfortunately not. The home section in the SmartThings mobile app is only used for smart home monitor at the present time. A previous version of the mobile app also had a few other things and those were Left over for people who have been using that version, so you might see some screenshots with additional information, but it’s not anything that a user can control.
Many people in the community use the third-party dashboard, SmartTiles, which can run in just about any browser and so works on most smart phones as well as tablets. It’s fully customizable, and not just as to which devices appear, but color and style as well.
Here’s the link for that:
www.smarttiles.click
There’s also lots of discussion of it in the forums if you look around.
People use it in many different ways. For example, you might want to use it with a housemate so that they have on/off control of some devices, but not all, and they can’t change any of the rules and automations that you’ve created. 
SmartThings has shown some early prototypes of more functionality / features being considered for their Dashboard page (that’s what the “homepage” of their App is called.
There used to be several, but dropped in App V2.
The prototypes included some basic “shortcuts”, but nothing particularly revolutionary has been revealed.
I think there’s plenty of potential.
However, as co-founder of ActionTiles, we obviously believe there is room for 3rd party apps that cater to particular markets and wishlists.