When my kids were little I did the standalone HEPA thing, never sure it did much tbh.
I have been buying the Filtrete 'Ultimate Allergen' 1" filters for my HVAC return (HP+AC) for over a decade. They are MERV 13. With that and the airsealing the dust and allergens in my house are MUCH reduced relative to before, with no airsealing and hydronic baseboards.
My HVAC dude told me to only use the (see through) floss filters, because 'pressure', but I measured the pressure drop across the filter (
) both new and at end of life and it was well below specs from the blower manufacturer (Goodman). Well engineered 'depth filters' which are stacks of sticky fibers, are not like a 'membrane filter' with pores of a certain size, like a sieve, and the pressure drop does not need to be high to get high capture. A plus, I reckon my ducts stay a lot cleaner inside.
I would trust anything in the 3M Filtrete line to NOT break my HVAC blower, contra what an HVAC tech would tell me.
Its not HEPA, but I figure it makes up particle removal on the volume (cfm). If I needed more filtration, I would do standalone on top of the HVAC filter, on a closed room basis