I think it should work ok.
The only potential interaction I’d worry about is where the generated C++ and then compiled .o and .so files are placed. By default they are placed in R’s automatically created temporary directory (which you can find by tempdir() ). I think each R session should make a distinct temporary directory even if they are sharing a file system, so you should be ok.
If you are providing a dirName argument to compileNimble (which would tell it where you want it to put the C++ and related files), then it could be a problem if they two processes share a file system and attempt to use the same directory for their nimble compilation.
But let us know if you encounter any other problem I’m not anticipating.
Perry