Thank you for your recommendations.
Yes, I assure you that I have already done in advance a quite wide search before asking.
Please note, that in my question I asked explicitly for free alternatives which rules out ggmap or any other solutions based on google API.
The third is an old article (5+ years), although the OpenStreetMap it looks promising this package was updated last time about 3 years ago, so it is questionable because the old java dependencies.