Assuming for a moment, for the sake of argument, that this plan would succeed in oxygenating the Martian atmosphere, what’s the time frame? The oxygenation of Earth’s atmosphere by microorganisms took rather a long time. Here’s one geochemist who says it took 250 million years….
"What it looks like is that oxygen was first produced somewhere around 2.7 billion to 2.8 billon years ago. It took up residence in atmosphere around 2.45 billion years ago," says geochemist Dick Holland, a visiting scholar at the University of Pennsylvania. "It looks as if there's a significant time interval between the appearance of oxygen-producing organisms and the actual oxygenation of the atmosphere."
https://www.scientificamerican.com/article/origin-of-oxygen-in-atmosphere/