RStudio has made packages for multiple versions of R available and described how to install them here: https://docs.rstudio.com/resources/install-r/ . That seems to work pretty well for installing multiple versions of R on the same box - this is something we like in my organization for testing.
Separately, Ubuntu (Debian, really [Dirk Eddelbuettel, really]) has created system packages for CRAN packages, which is fantastic for rapid installation, getting system dependencies right, etc.: https://cloud.r-project.org/bin/linux/ubuntu/README.html
Is there a way to have both benefits at once? In other words, install several versions of the Ubuntu R packages on a single system, and be able to install CRAN packages by using apt to install them as system packages, rather than using install.packages() in R?
The Ubuntu installation method described at the page above leads me to believe that the versions of R are mutually exclusive, because you set the version by choosing a corresponding apt repository, and the packages themselves (probably?) conflict across versions. Is this correct?