I have two rasters I would like to merge and also fill in no data cells along the boundary between the two rasters to create a smooth transition. Some of the cells along the boundary are no data cells, and they are not filled when I try the Mosaic raster layers tool by SAGA. I have tried both the feathering and blend boundary method for the "overlapping areas", but I suppose this only applies to the areas that actually overlap. Therefore, I'd like to feather/buffer my raster boundary to create data for the existing nodata cells for cells which are an x distance away from cells with data, similarly to how the built-in buffer tool for vectors works.
Is this possible with any built in tools in QGIS?
I've attached an image of my output from the Mosaic raster layers tool.