Zinfandel first, among others.
16 years ago, I was assigned a Zinfandel wine-pairing project and once I tried pesto pizza with Zin, I was sold. The two work so well together. The pungency of the basil and garlic, working with the Parm, are magic with Zin's fruit and peppery spice. (And, it's best if the Zin has a slight peppery-ness, which it will if it's true to form.) Sausage will only add, though it seems like pesto + sausage is a wild flavor-topia thing.
In truth, many red wines will work. Chianti, Barbera, and on and on. Even a cold Rose will work, or better yet, Rose Champagne, especially with the sausage.
Some white wines will work, with qualifications. Pesto is from Liguria, where Vermentino is king, and that crisp white wine works well with it -- provided the pesto is more Genovese or Ligurian in character, and not like American-Italian pesto. The Genovese/Ligurian pesto is a luscious, silken green paste and not nearly as pungent or thick as US pesto. It has less garlic and less cheese -- so the Vermentino white wine works. It might work even with the sausage added too. As the intensity of flavors on your pizza builds, the wine will have to match accordingly. Have fun and report back.
Please see this post
Wines with pesto...aioli
(with commentary by the brilliant Melanie Wong):
Just looking at Pesto in isolation, I personally tend to favor whites.... my favorite probably being sauvignon blanc. Gavi and Pinot gris also quite interesting...
But when you start adding "pizza" ingredients, sausage, cheese, etc. the wine pairings can get blurry, and red wine opportunities open up. While I can see zinfandel here, I'd also look at a somewhat softer and pesto-friendly wine, Valpolicella superiore.
Actually, this would be a great pizza to serve BOTH a red and white with.