You are correct, if you apply a view limitation to the page, it will limit the data displayed in all resources added to the entire page to the set of objects you limit it to.
I currently don't have access to test this, but it will be easy to try, and you will learn how valuable custom object resources are to custom dashboards in the process:
create a new summary page and add "custom object" resources to the page.
Preview the page and click Edit on one of the custom object resources.
Select "AppInsight for SQL: Applications" from the object type drop down
For Object(s), Select the Appinisght for SQL applications you want to include in the resource
Select "Applications" for Object Resource
This will display the health roll up health status for each AppInsight for SQL Application Monitor that you chose for Object.
You can do the same for all AppInsight Monitors by selecting them in the object type drop down menu of the other custom object resources
Play around with the custom object resource options and preview them via trial and error until you get what you want displayed. I have another good idea that may be better in another reply.
You could also accomplish this in Network Atlas, a program that resides on the Orion application server. Open Network Atlas and create a new map so that you have a blank background. On the left side of the screen, is a list of all Orion objects that you are monitoring. Look for your Applications, and drag and drop them onto the map. For example, all of your SQL application objects. You can right click the objects to change the appearance/icon. You can also use a background image if you want. Play around with it until you get the Application Overview "map" the way you want. Save your Application map.
To display it in the web console, add the resource called "Map" to any one of your dashboards or a new summary page. Preview the page or submit it after adding the Map resource. Click on Edit in the Map resource and select the map you just saved in Network Atlas.