
A reader has created a new free iPhone app called GRPS that offers seamless geotagging for Ricoh GRIII cameras:
You can now buy optical waist-level viewfinders for Ricoh GR cameras on Ebay and Aliexpress. The viewfinders have different frame lines (28mm/35mm/40mm/50mm), so make sure you pick the correct version (two different models are available). More Ricoh GR accessories can be found here. Additional pictures: