None of these small browsers can make significant changes to the original project. A browser nowadays is a super complex bloated thing that requires too much resources to maintain. If even M$ abandoned their engine to go with Chromium (because it was probably costing them a lot of resources to keep compatibility with the evolving standards, security fixes etc.) what hope is there for small companies? Arguably Apple’s Safari has significant differences compared to Chrome, but we’re talking about Apple…

People thinking this is a solution are gonna get disappointed eventually. For now, Firefox is the only alternative product that has been maintained for decades.