Do you know upfront the number of files you are going to read (and maybe also their names)? If you do, how about using something like a_ply, that has a built in progress bar (see the .progress argument --- it's a text style one but I find it useful, as it also shows the actual percentage). In the case of a_ply it gets an array, e.g. with the names of files to be loaded, runs a function that you specify on each (e.g. loadRDS), and updates the progress bar on each iteration. That's the simplest "of the top of my head" solution that comes to mind, I may be able to think of other things along this line if that's not sufficient.