It feels like the company gives its employees a fairly free working environment.

There is a written test for the firmware engineer interview, but the questions are nearly deliberately tricky and do not align with the actual requirements of firmware work. I seriously doubt that this approach can identify engineers with genuine hands-on abilities.

During the interview, the manager mentioned that the company places great importance on applicants’ cultural fit. However, of course every applicant will simply agree with the manager. Moreover, based on my experience working at startups, I have deeply realized that people who have never truly worked at a startup will quickly burn out after joining their first one. Your company should be looking for applicants with startup experience—those who can stay are not necessarily the ones who identify with your company’s culture, but rather those who enjoy the autonomy of startup work.

I strongly recommend that your company place more emphasis on applicants’ past backgrounds rather than their written-test scores. Especially for a startup like yours, the people who are willing to stay are not necessarily those who score highly on the test.