Well, if what makes a mid to senior front-end engineer is "extensive experience in react and its ecosystem" and you "don't have a history of working on mid to l

Well, if what makes a mid to senior front-end engineer is "extensive experience in react and its ecosystem" and you "don't have a history of working on mid to large scale react projects", then the only way to get that dream job is to gain more React experience. One or two more years spent freelancing on carefully chosen projects should be enough. But the wind is turning: if you can, splitting your efforts 50/50 between React and Vue projects would probably be a good idea.