Intentionally radically altering the climate of large areas like the Sahara seems very dangerous in a way that nothing that could be done on other celestial bodies could ever be. Not that it shouldn’t be considered, but I think it calls for a far greater degree of caution than e.g. experiments to bring life to small domed areas of the surface of Mars.
If you have the technology to make small domed oases, make them in the Sahara (or Antarctic, or wherever). No need to change the climate, and you save the cost of a Mars trip.
Going to Mars is a legitimate goal.
But i would also like to see a make-the-Sahara-green-(ish) program.
Why not a Neom-but-in-a-viable-way program.
ALso, an even bigger debate is Appolo-mission-to-Mars vs 10-other-unmanned-programs-for-the-Solar system.