Well we've got everyone in our extended family air filters. We ended up getting a HEPA filter made by BlueAir called the Blue Pure 211+ for $300 at Amazon. I can't actually tell if it works, but it is quiet.
The other company that has gotten buzz has been Molekule. They have an additional filter called PECO which is a variant of PCO. It's a classic battle between Silicon Valley and traditional reviewers. For sure it doesn't process air that efficiently, but they claim the can denature viruses and other things. The site says they can eliminate 99.999% of a virus as small as COVID-SARS-2. I don't know whether to believe them, but it will be interesting to see a real test lab compare them. Consumer Reports says that it doesn't filter well and Wirecutter says it is not fast for particulate.
Technically what they are doing is they have a MERS-16 filter (so close to HEPA) for gross particles but then have their own PCO (Photocatalytic Oxidation) which basically has a metal and light so it destroys more complex molecules. So it is a two step process and it isn't clear whether it works or not.
And like all cool high tech gadgets, the Micro+ includes an air quality monitor as well as being Homekit compatible which is pretty neat. I might have to get one just to try it.
Also like other disruptive startups, it could be a Tesla, where the critics were wrong, or Theranos, where the critics were right.
It is also expensive at $349 (on sale right now) plus $120 a year fore new filters, so we ended up using the more traditional PureAir Blue211 until more data comes out. They also now an FDA approved high end version of this for hospitals that sounds cool called the Air Purifier Pro RX but that high end thing costs $1,100 for the residential version!