Currently, I'm using

rlang::inject(job::empty(!!var1, !!var2, ...))

to make sure that I pass actual values to the code, and not the variables (which may be available with the default import = "auto", but I never tried). If job used rlang to capture the expressions, I could avoid the inject() .

For portable function calls, have you seen the carrier package? https://cran.r-project.org/web/packages/carrier/index.html