What are the approaches for complex testing of embedded devices?

Question

Software testing

Hello, share your experience of covering Embedded products with tests from unit tests to system tests.
Now there is some unit coverage with GTest. There are thoughts for subsystem and system to use Gherkin / Cucumber, but in relation to C ++ or Python, not everything is as good there as, for example, for JAVA or C #. Maybe someone built a complex solution and how to combine it all into a single report? So far, only ideas are on the side of a test management system, such as TestRail. Tips on integration tests will also be helpful.