If you want typing in Rails, you're in reality itching to try Crystal lang and most likely Amber framework. Much faster too as it's a systems language.
I’m itching to try Crystal, since it has goroutines aka. greenthreads aka. fibers for easy concurrency, static types, automatic null checking, and performance on par with Golang.
But Crystal has around 468 open bugs at the time of writing :(
I did run a startup for a year that was on crystal, and I will say the community is quite good at addressing real bugs. There are a lot of "you don't know what you're doing" bugs and "this is already fixed but you haven't updated" bugs and "this is really a feature request" bugs in the tracker. I wouldn't read into it much. There hardly exists a popular programming language or framework without at least several thousand open issues.
Sorbet is trying, but it's... not there yet (although getting better).