The linked pages provide pointers to a gazillion R
packages which do Kriging or other interpolation functions.
I'm posting my personal choice as an answer just to close out this question.
I found akima::interp
to be a straightforward function to do 2D interpolation on arbitrary collections of sample locations.
That doesn't mean it's going to be best for everyone, and my guess is those working with geodata may prefer packages designed to muck with specific geo-survey-related file types and lat/long coordinate systems.