If Clojure and Rust work well for you, more power to you. But at least in theory, you could very well use just Scala for these purposes
Scala can compile to JS https://www.scala-js.org/ if you target frontend.
And if you want portability, you can compile a Scala program with GraalVM's native-image and statically link everything with musl libc https://www.graalvm.org/latest/reference-manual/native-image...
And if you want both frontend and portability everywhere, Scala will soon have a support for compiling to WASM (with WASI, etc) https://github.com/scala-wasm/scala-wasm/ (to be integrated into Scala.js after developed)