Definitely! There's still a lot of unknowns in the microbiome space, and it's something we hope to look into as we gather more data. Some studies have suggested that adolescent oral microbiome profiles can serve as indicators of future health outcomes. Review here: https://pubmed.ncbi.nlm.nih.gov/32350240/

Have you considered complementing DNA testing with selling specalty augar (to detect Streptococcus mutans for example) and instruction manuals with an online forum?

There is, look into K12 and M18, species of streptococcus salivarius with proven oral health benefits. They are available as supplements, and in New Zealand they officially use these to treat children with recurring nose/throat diseases. Studies back this up.