I think a core useful functionality of the package that would interest us would be: functions to download, cache, and pre-process the raw data from NOAA. For instance, a function could take a bounding box or polygon as an argument, along with with date and image series, download the appropriate tile if it's not already cached and return a matrix or raster of the requested area. (Similar to the ccafs package) Anything on top of that, such as calculating irradiance across the tile or related statistics of interest, image processing, would be gravy in the package, and in fact we avoid methods-heavy packages as we have less expertise in reviewing field-specific statistical implementations. We would prefer that the package aims to perform the download/clip type tasks as speedily and efficiently as one can on local machines, rather than drive users to a service (and can help with how to do that). But if the service is providing a useful additional task or making the process faster for people, even if its just hosting much smaller tile sets to make user work flow more efficient, I have no problem with it having a commercial model. If core functionality is in the paid service, given that the data is free we wouldn't accept the package (though others, such as cloudyr or JOSS, would).
I know you can already grab and import data from GADM using
raster::getData() (I think they provide it as .Rdata files), not sure if that's built in to any of other or our own packages.