Ladybird will be a Firefox alternative, nothing more. It can't be, by definition. People are not using Chrome, Edge or Safari because they're great browsers. They use it because it's preinstalled and good enough. They don't care, and they won't care in a future where Ladybird is a thing.

Ask 60% of their (Chrome, Edge, Safari) userbase, and they won't even be able to tell you what their browser is called.