Count up or down to days app suggestions

As I am setting up Obtainium I was evaluating a simple app which I figured there has to be some FOSS alternative or GitHub project that would be better than getting an app from Google Store. I am surprised I do not see a better option.

I have use some simple search terms in F-Droid and on search engines with no good results. The apps reviewed on seem like worse options with size, permissives and even trackers.

I share here for alternative suggestions and as my best option for counting up or down to days. I use this app for planning task.