To install multiple kernels from multiple conda environment so that they are visible from another environment, in the jupyter notebook, I followed successfully these instructions for Python: https://ipython.readthedocs.io/en/stable/install/kernel_install.html
And these instructions for R: https://github.com/IRkernel/IRkernel
For R, there are issues. I've created a R conda environment first, but it may not be needed. It may be better to try other ways, where one has more control over the installation.