Opening a project per default

I am currently working on a Docker container image for a single R project.
Therefore, I would like RStudio to open the project automatically by default.
Unfortunately, I only found a setting for the default directory (cf. RStudio Workbench Administration Guide - Appendix A — Session User Settings) which I currently set in the Dockerfile like this:

RUN echo "{ \"initial_working_directory\": \"~/path-to-project/\" }" > ~/.config/rstudio/rstudio-prefs.json

The user then needs to click the .Rproj file manually.
Is there any way to open a .Rproj file directly?