You need a lot of air to overpressure a space. I work in / around overpressured workspaces and the system requires both recirculating and makeup (as in take in more from the outside) air handlers. While some of that extra air is needed to replace all that is being exhausted out from / thru the equipment in the workspace, some of it is there just to overpressure the building.

I don't think there is any way for a home system to do overpressure a home as it doesn't have all that extra air to use.

As for filtering, I know they use *big* pleated filters on the intakes; I'm not sure what else is inline.