You can move the air filter closer to the actual opening of the duct work down in the bay. Where it won't be visible.

Installing insect screen to make the filter less visible will affect the performance of your system. Proceed with caution.

There are filters with activated carbon that are black. Here is an example:

Pleated HVAC AC Furnace Air Filters Replacement with Activated Carbon

These filters are usually almost black in color. The carbon is supposed to reduce odors. I have never used this type of filter. The paper frame is still white. If that is noticeable you could go over it with a black magic marker.

Doesn't your filter grill have downward facing louvres? If not, can you change it?

Not sure—Will check. Thanks!

Thank you!