Nukit - Tempest - PC Fan Air Purifier Kit (US)

This is the way. I have one in every room. Have standard HVAC 16x25 filters which I pickup from Costco, far cheaper and way more surface area than any other option. Been considering upgrading to the Nukit Tempest, which essentially has a metal frame and takes 2" filters

So for air purifiers to be effective they need to be sized appropriately. You can either guesstimate based on size of space, or per occupant. Better to do both and go with the bigger size.  Per occupant- you need at least 30cfm/person.  Size- volume of space and CFM of unit you can work out how many minutes it takes to clean the space- you want less than 20 minutes or 3ACH (air change per hour) at minimum.  Cheapest purifier for cfm/$ is a CR box made with Costco 3m 2500 Filtretes and a box fan.  Nukit Tempest is good, reliable, quiet, and runs forever with easily repairable parts.  If you don’t have enough filtration, and you don’t have air mixing to make sure it all gets to the filter roughly evenly, it won’t be all that effective. 

Do get a robot vacuum that vacuums daily though. Then get 2x Nukit Tempest purifiers. One near your bed and one whenever else makes sense (probably near your dusty couch). Get more of them if your space is larger. One per room is way better than one massive one in your livingroom. I've got both dust and pollen allergy. Before I used to wake up with my nose pretty much airtight and with runny eyes. Now it's as if I'm not allergic at all. My goal was to maximize CADR (clean air delivery rate) at a noise level that's inaudible with minimum power use and low running cost in replacing filters. I've made my own purifiers based off the Corsi-Rosenthal r/crboxes principles which states that CADR goes up if the filter has near zero resistance. This concept was thought up during the pandemic. Most commercial purifiers have higher resistance through their filter so they have to use noisy and power consuming centrifugal fans to get adequate pressure. They also use proprietary filters which clog up yearly because they're undersized. Lastly, forget about the charcoal filters. Volatile gasses are not your issue so the charcoal will only make the purifier less efficient at what you need it to do. (Edit, I just saw the smoking part, I feel sorry for you)

Nukit Tempest. Most airflow for your money, and once you buy the frame you're not reliant on a company staying in business or continuing to make filters/parts for it. Everything inside can be replaced with common parts.