Brothy Meatballs with Peas

2 Tbsp. (or more) extra-virgin olive oil, plus more for drizzling

3 large shallots, thinly sliced

4 garlic cloves, thinly sliced

2 medium fennel bulbs, halved, cored, very thinly sliced lengthwise, divided

Kosher salt, freshly ground pepper

4 cups low-sodium chicken or vegetable broth

3 Tbsp. white wine vinegar, divided

2 cups pea shoots (tendrils)

½ cup torn dill

½ cup parsley leaves with tender stems

8 oz. sugar snap peas, thinly sliced on a diagonal (about 2 cups)

2 cups shelled fresh (or frozen) English peas and/or shelled fava beans

3 cups cooked fregola, Israeli couscous, or farro

Aleppo-style pepper (optional), lemon wedges, and grated Parmesan (for serving)