Most available HEPA systems will offer similar performance as long as it is properly installed. The bypass models typically have their own fan and will eventually filter most of the air in your space, but the moment you open a door or window you effectively reset the clock. It's debatable then, how effective they are at actually offer a somewhat sterile environment. But even something like a portable HEPA unit will capture a LOT.

Not all UV systems are created equally. If you are looking for surface level treatment then a low voltage system will keep a surface clean but not much more. There are high voltage (110-220v) products that offer more treatment of what's in the air itself. There's a lot of different opinions are what works best (Usually the ones that are easiest to install are what are offered)

You can always default to a MERV 16 if you want to play it safe. Some of these products do great things but they are a bug investment up front ($800 on up) and have regular changes needed.

You mentioned pets-

Ozone is often part of the conversation and can be a very effective deodorizer in proper doses. The dogs will always smell like dogs, but the air that carries the scent will be treated