Desktop software to view observations ?

[R5ph4]

With features -
1. Offline - I don't want to upload to wigle.net
2. with different maps like OSM and Google etc.

[zebul666]

That's not what you asked but here is a solution to your problem.

I have made a simple python script that convert a wigle csv file to a kml or gpx file.

Then, you can use google maps to visualize the resulting kml file, or any gpx viewer like gpxsee to visualize the resulting gpx file.

[pejacoby]

You can also turn on Settings > Map Settings > Log routes for execution, and then use the Database > Saved Routes screen to export GPX to export files that can be viewed in a variety of GPX apps on the desktop.