This could be a killer, missing feature in SmartSuite. Create a new function to be used in formulas that provides the ability to lookup and return data in a different application based on field data in the current record where the formula is being used.
Syntax example: LOOKUP([Current_App_Field],[Solution].[App].[Field],)
The formula instructs SmartSuite to look in the specified app for a matching value from the specified field in the current app, and then returns the value in the specified field in the app to which the function is told to lookup a value. This could emulate linking without having to manually link records or create an automation to do the linking. Would be very valuable.
Requirement is that lookups probably could only be performed against fields where unique values are required (as in primary keys) or you would have multiple record matches.