Niger has had to my understanding significant recent success concerning its ecological policy, or more precisely ecological developments in lacking one. They had had a rather bad policy inherited from colonial days, (and hardly unique to them, plenty of other states had equally bad policies) which effectively encouraged chopping down trees, placed forests as state property that nobody was interested in maintaining, and encouraged mono-culture. It was only recently that this shifted to farmer-managed natural regeneration where farmers don't plant trees themselves but instead focused on preserving and cultivating trees that were themselves growing naturally, and didn't clear their fields to destroy them. This has been of great help in enabling a much large number of trees to be cultivated and most of all maintained since a critical difference was that previously huge number of trees were planted but nobody bothered to take care of them, so they all died. There has been a resultant huge increase in the number of trees, many millions of hectares, and these trees are much more effective in weathering climatic problems and countering them, than previously. If this change could be implemented earlier, then it could do much to help confront the tremendous drought and ecological problems of the 1980s.
Now how to achieve that? That is the hard part. There has to be an awareness that the different method of tree planting, and it has to be effectively spread. I don't think Western NGOs are a good agent to do this, and nor is the government. Instead, when this starts developing in from what I understand was the early 1970s, it has to capture the attention of somebody with important status in the civil sector, maybe a religious leader, and be more widely adopted. That would help to avoid the drought and ecological catastrophe of the 1980s. It would not make Niger into a developed nation, but it would leave it with a more vibrant and protected agricultural sector and less scars from environmental catastrophe.
The other thing is that preferably the population would not grow as much. The number of children per women has been falling, but the population has exploded by a vast number. For a Sahel country, with an inherently ecologically fragile zone, going from 2 million people to 17 million is taxing. An industrial economy can absorb that, but if your population is inherently living off of the primary sector of the economy... well, that's not good at all. But getting an effective family planning program early on in Niger seems even harder to me.
Those borders were certainly not drawn up by idealist Westerners. They were drawn up by Westerners who were creating their colonial administrations and territories, not out of any sense of "idealism". There were a variety of ideas provided in Afrique occidentale française concerning redrawing the borders to fit ethnic and religious realities (which probably would not have worked very well because the French administration naturally had problems with getting good ethnographic information, and the actual situation on the ground in Africa is very complex and diverse). As far as changing those around post-WW2, well in my opinion as far as continental wide redrawing, that's even worse. People focus on the destruction of tribal and traditional identities, and to some extent that's true, but that's what any nation-state should be doing in the long run. The nations which emerged were fragile but they nevertheless did have a national identity, and tearing that, at any time post WW2, is going to be incredibly destructive and take a very lengthy time to be able to put Pandora's box back together, because it sabotages and underlines the national identity and nation-state process. I've argued in other threads that Africa would be better off without colonialism, but once the colonial structures are in place, the sunk cost in them means that changing them around is prohibitively damaging.