- There is a specification for a tail call instruction in wasm. github.com/WebAssembly/tail-call https://v8.dev/blog/wasm-tail-call
- Browsers, e.g. Chrome, implement this. https://webassembly.org/roadmap/
- At least one scheme implementation called Guile-Hoot targets this https://gitlab.com/spritely/guile-hoot ABI spritely.institute/Status
This spec seems to have gotten in thanks to work by apignotti, https://hn.algolia.com/?q=WebAssembly+tail+calls
There is also a very interesting project for generalized effect handlers that may build on top of this platform https://wasmfx.dev/community/
Great news for schemers with web browsers.