Research in child day care centers in Helsinki shows purifying the air reduces infectious illness by almost 20%, and that purifying the air in all public spaces should be examined.
I am not one of those anti-vaxx loonies who are like "you got an immune system so you're fine without all this crap", however isn't it an accepted view that the immune system needs training to operate well? Hygiene hypothesis comes to mind and especially during those years as a child many parts of the immune system are forming and developing.
Going too clean everywhere will counter that and lead to worse outcomes later in life if you get sick with something.
So while I sympathise as a parent with a preschooler who is terrible when sick, it is useful to not be too super clean in that environment.
Now in areas where more grown-ups are working, office spaces and so on, sure. Not quite against that.
I admit I don't know very much about any of this, but I've never heard of children who grow up in relatively isolated circumstances, for example home schooling, having lower functioning immune systems?
I can't find anything on differences in indoor hygiene causing a difference to the immune system. Homeschooled children will still be exposed to the same viruses through their parents or anyone else. It may very well be a misunderstood study from the 80s. It is currently neither confirmed or proven wrong.
However I've found a slightly different study. It compares children who go to conventional kindergartens to children in outdoor kindergartens.
I'm not sure if you're familiar with that these "forest-kindergardens", but the general idea is that the kids are outside all day. Due to the need for warm clothing and constantly getting dirty, they usually wear the same outdoor suit throughout the week. They're exposed to natural bacteria a lot more, but less so to airborne viruses.
So it's not exactly the same thing you asked for, but it does show a difference in their immune systems.
The problem is when you are constantly sick because of the school, its a real problem my family in Florida faces every school year. I visited them this last year during the spring and they were sick for the entire visit and apparently it happens every year now. Plus, after covid everything seems like it got much worse on the preventing infection side of things, so this tech would most likely be a net positive, even if it does affect the immune system and its natural defenses.