Fair objection. But I believe that Hazbin Hotel is a project that is on a way larger scope.
Vivz said things like "Hazbin Hotel is my baby", so I like to imagine its way more important to her and it takes much more time.
In the end, a lot of shows get an entire season filmed and even produced before even a single trailer gets out.
Oftentimes Netflix drops an entire season at once.
Helluva Boss is different for her, it's more of a "playground" appearently and she doesn't take it aaaas serious as she does Hazbin Hotel. And the contract may allow them more leeway with the release schedule.
I will say though, I'd like to see a trailer sometime soon, or any kind of updates.