Software development often takes a lot of time but its impact is often difficult to evaluate. If you have developed an R package and upload it to CRAN, you might be able to get some download information but not a lot.
Since R studio hosts the CRAN mirror, it keeps tracking the download statistics of the R packages installed from the RStudio mirror and therefore provides some useful information. It also provides an R package -cranlogs- to get the information within R. Certainly, the information is not incomplete but at least it provides the developers some ideas on how their packages are used.
For example, the code below is used to get the download information in the past month of an R package coefficientalpha I developed.
library(cranlogs)
cran_downloads('coefficientalpha', when='last-month')
date count package
1 2019-04-08 15 coefficientalpha
2 2019-04-09 15 coefficientalpha
3 2019-04-10 25 coefficientalpha
4 2019-04-11 18 coefficientalpha
5 2019-04-12 25 coefficientalpha
6 2019-04-13 13 coefficientalpha
7 2019-04-14 11 coefficientalpha
8 2019-04-15 22 coefficientalpha
9 2019-04-16 15 coefficientalpha
10 2019-04-17 31 coefficientalpha
11 2019-04-18 11 coefficientalpha
12 2019-04-19 19 coefficientalpha
13 2019-04-20 14 coefficientalpha
14 2019-04-21 14 coefficientalpha
15 2019-04-22 19 coefficientalpha
16 2019-04-23 6 coefficientalpha
17 2019-04-24 21 coefficientalpha
18 2019-04-25 19 coefficientalpha
19 2019-04-26 7 coefficientalpha
20 2019-04-27 11 coefficientalpha
21 2019-04-28 13 coefficientalpha
22 2019-04-29 38 coefficientalpha
23 2019-04-30 14 coefficientalpha
24 2019-05-01 18 coefficientalpha
25 2019-05-02 18 coefficientalpha
26 2019-05-03 10 coefficientalpha
27 2019-05-04 3 coefficientalpha
28 2019-05-05 15 coefficientalpha
29 2019-05-06 58 coefficientalpha
30 2019-05-07 39 coefficientalpha