I would keep Python and R packages in different environments. The Renv package provides tools for managing different R environments.
The benefit of conda for Python is that it provides robust build instructions, so that Python and its related dependencies generally "just work". For R, CRAN enforces this through the package submission process (and R packages in general seem to deal with dependencies better IMO), so in the case of R the benefits are mostly for reproducibility with specific package versions.
Best,
Randy