Why not go full elm? It is not at a major version release. There were some breaking changes from 0.18 to 0.19 that while well documented is indicative of the state of the project. The language is taking its time to be written well, which I do not fault, but makes it hard to justify using it. I could incrementally adopt it, but then that would be another language someone using my project would have to learn. I am using connect rpc which compiles grpc to js, I would need to write some elm ports to hook those up or port the transport to elm. Not impossible, just work.
When do you take a risk on a language? When you are dealing with such low stakes with coding, as is often the case with a personal project, why wouldn’t you take these risks? I have rewritten many projects in my pursuit of finding a stack that “feels right”. Is elm a part of it?