Apparently even metal trees take time to grow.
Using micro algae to clean air isn’t a new idea, there was another startup almost 10 years ago that was designing outdoor lighting that grew micro algae for the same purpose. There’s DIY maker blogs on how to do this small scale for your home.
You could probably have a home setup that you occasionally purge the surplus algae into your compost to clean air and enrich your soil at the same time. The ones I remember would use water from local natural sources like rivers or just leave the water outside for a few days to get infused by the micro algae so as to avoid accidentally releasing invasive species in the wild. The rest was just adding nutrients , proper lighting to make it look cool, and pumping air through it to aerate it.