Absolute QGIS newbie (3.10.8) here, so please bear with me.
I got a QGIS document where some polygons (countries) are virtually dissolved in regions (like South America), through a rule-based symbology and styled as one polygon with the geometry generator.
buffer (collect($geometry), ' ',(array_contains(array("Reg1" ,"Reg2" , "Reg3"),'Region_name'))),0)
I want to export a file (preferably .shp) of these regional objects into dissolved polygons based on the attribute "region_name" when it occurs in one of the fields "Reg1", "Reg2", "Reg3", some countries being part of several political or economical region (South America as a geographical ensemble where some of the countries belong to a specific economical institution and some other not)
How do I do that?
Edit: Value and field names, explanations