A certificate is safety. Traffic rights are separate.
You can operate commercially while your own certificate is still in progress, with an established operator carrying the AOC and you carrying the brand, the schedule and the commercial risk. It is how a good many airlines actually started.
The distinction that catches startups out is that a wet lease does not confer traffic rights. The aircraft flies on the operator's safety certificate, but the flight is sold under your operating licence, and route authority attaches to the licence.
