I applied to the position through a StackOverflow Jobs posting. I had to answer three developer-related short answer questions, and within 5 days or so, I got an email back from a recruiter.
The recruiter then set up a phone interview with me to get to know me better and to explain exactly what the OnSite positions are (which is loosely their contractor program). After the phone interview, I was sent a React-Native code challenge which I completed the following day and sent back to the recruiter who then forwarded it to the OnSite client. I got a call back saying they liked my code enough for an on-site interview (at the OnSite company, not at Detroit Labs).
The interview at the OnSite company happened about a week later and it was an hour and half coding session where we discussed and reviewed the code challenge I submitted. The team I interviewed with was extremely friendly and the coding session was more of a conversation rather than a rigorous interview.
I got a call back the next day with a great offer! I ended up turning it down but both the Detroit Labs team and the particular OnSite team have made the experience extremely positive. In particular, the Detroit Labs team has made it clear that they care more about your personal growth rather than your labor power.