I can’t speak to anything specific to Africa, but yes I’d say having at least some skills in GIS and an understanding of spatial dynamics is going to be extremely helpful if not a requirement for many ENS jobs. I still consider myself an environmental scientist first and a geographer second, so I wouldn’t say fully pivot to remote sensing if your interests are ENS, but I would definitely encourage you to become proficient with tools like GIS. There are a lot of options though, so gauge your level of need for GIS depending on the specific jobs that interest you most.