While all that was happening 10+ years ago, I learned about DO-178B. I have a copy of the DO-178B spec within arms reach. And I found that, unlike most other "quality" standards I have encountered, DO-178B is actually useful for improving quality.
I originally developed the TH3 test suite for SQLite with the idea that I could sell it to companies interested in using SQLite in safety-critical applications, and thereby help pay for the open-source side of SQLite. That plan didn't work out as nobody ever bought it. But TH3 and the discipline of 100% MC/DC testing was and continues to be enormously helpful in keeping bugs out of SQLite, and so TH3 and all the other DO-178B-inspired testing and refactoring of SQLite has turned out to be well worth the thousands of hours of effort invested.
The SQLite project is not 100% DO-178B compliant. We have gotten slack on some of the more mundane paperwork aspects. Also, we aggressively optimize the SQLite code base for performance, whereas in a real safety-critical application the focus would be on extreme simplicity at the cost of reduced performance.
However, if some company does call us tomorrow and says that they want to purchase a complete set of DO-178B/C Level-A certification artifacts from us, I think we could deliver that with a few months of focused effort.