A service where I can `git clone` a repo and that is what starts the timer for the coding challenge is a great idea.
When I was recently job hunting, I had a bad experience with a company that wanted me to take a timed coding challenge where I would clone a repo and then submit a pull request with my solution. What started the timer then was them opening the repo to me, not me accessing it. This required us to agree on a time for me to take the challenge. Long story short, the recruiter proved incapable of opening the repo at the times we agreed on.
Avoiding that need for coordination and chance for the recruiter to mess things up is a nice benefit of your service.
When I was recently job hunting, I had a bad experience with a company that wanted me to take a timed coding challenge where I would clone a repo and then submit a pull request with my solution. What started the timer then was them opening the repo to me, not me accessing it. This required us to agree on a time for me to take the challenge. Long story short, the recruiter proved incapable of opening the repo at the times we agreed on.
Avoiding that need for coordination and chance for the recruiter to mess things up is a nice benefit of your service.