TL;DR
The rw R package allows you to evaluate R code within R WebAssembly as implemented by webR, e.g.
> rw::rw_do_call(Sys.info)
sysname release version nodename machine
"Emscripten" "4.0.8" "#1" "emscripten" "wasm32"
login user effective_user
"web_user" "unknown" "unknown" This can be useful when we need to evaluate arbitrary, untrusted R code in a secure manner isolated from the host system. It is also useful for making sure R code and R packages work in webR without having to go the extra mile to upload packages online and then testing it in the web browser at https://webr.sh/.