> But, yeah, we're having a hard time finding full-stack people that can hit the ground running with Java and Vue

Why not get people who’ve worked with Java and other frontend frameworks, or Vue and other object oriented languages? In my first coding role I knew absolutely no C#, just some JS but I was contributing to the codebase within a week. Most of the particulars of your codebase will be particular to your codebase. Find people who’ve shown they can learn and give them a few weeks rather than take months to hire a person who has last worked with your particular stack.