That's really good input, thank you. I spent more time with the documents and I see that I misunderstood some of the documentation. non-conda virtual environments are supported and I was even able to get Pandas installed!
For future Reticulators that find themselves here, I'll leave some breadcrumbs that I found helpful:
Reticulate and RStudio Cloud puts virtual envs in a special directory:
> virtualenv_root()
[1] "~/.virtualenvs"
If you have virtual envs installed in other places, commands like virtualenv_list() won't show the environments in other places. This confused me at first but makes sense in retrospect.
So to install pandas in a new virtual env, the following works in in RStudio Cloud:
virtualenv_install('my_new_env', 'pandas')
Now when I create Python code chunks, I start them with
use_virtualenv("my_new_env")
and things seem to work as I would expect them to.
That said, I'll happily switch to an Anaconda based workflow when that's available in RStudio Cloud
-J