Make Deploying and Testing Custom Developed Visuals in Power BI Desktop as Easy as Power BI Online

Deploying and testing custom visuals in Power BI Desktop requires removing and re-adding custom visuals from the *.pbiviz file.

I would like the workflow of deploying and testing custom visuals in Power BI Desktop to be as simple and easy as in Power BI Online where the custom visuals are updated automatically as a new *.pbiviz file is built.

Why? Not all data sources can be used in Power BI Online (e.g. Azure SQL Database), making developing custom visuals for such data sources cumbersome.