Unlike most other statistical software packages, R doesn't have a native data file format. You can certainly import and export data in any number of formats, but there's no native "R data file format". The closest equivalent is the
loadRDS function pair, which allows you to serialize an R object to a file and then load it back into a later R session. But these files don't hew to a standardized format (it's essentially a dump of R in-memory representation of the object), and so you can't read the data with any software other than R.