It is, but I am ethically bound to not work on any project that has military funding. In general, engineers and software developers need to make better ethical choices.

How much flexibility do you give yourself?

For example, if a project uses a GPS receiver or GPS data, is that ok?

limited in scope and application.

In the book Sapiens, Yuval Noah Harari makes a pretty strong argument that military spending has a very broad impact.

It always blows my mind that all of the Lambda-the-Ultimate papers were sponsored the Office of Naval Research.