Eastern Red Ceder is very similar to arborviti but Native to New England and has bluish berries some birds eat.

American Holly has a solid "hedge" look and berries birds eat. Easy to grow.

Bayberry isn't that tall but has fruit.
There are native versions of Arrowwood Viburnum and Elderberry (Sambucus canadensis)

Beach Plum is a Native with fruit but isn't thick enough to provide much privacy.

Eastern White Cedar is native to northeastern North American, and is arborvitae. (Thuja occidentalis)

For 2/3rds of the property line, I'd want more of an idea for a plan than simply a privacy screen. If the idea is to simply continue the current plantings, then unless the character of the space changes, a change in plantings is probably going to look weird. Possibly it can work if the property line is long, and the change is drastic, like azaleas. (many of which are native)

Hello,
Well, unfortunately, we're talking about only 24 feet of open space along the property line. The main reason for planting is to hide my neighbor's backyard because it's looking like he's planning to spend a lot of time outside. So, it's his back door, which is located right in the middle of his house, probably right where the open space begins.
I am planning to have the existing arborviti cut back so they're all around six feet. Does that help in any transition? Can I put in a flowering something where his back door and then continue with a different series of something hedge or trees?
Thank you.