Divide dill, coriander seeds, and fennel seeds evenly among six 8-oz. resealable plastic containers, jars, or small bowls. Place chiles, fennel, scallions, celery, carrots, and/or beets individually in a container, followed by a generous pinch of kosher salt. Whisk vinegar, agave, and 1/2 cup water in a measuring glass; pour over vegetables. Cover and chill at least 12 hours and up to 2 days.
Whisk mayonnaise, mustard, lemon juice, turmeric, and cayenne in a small bowl; season sauce with kosher salt.
Cook eggs in a large saucepan of boiling salted water 8 minutes. Transfer to a bowl of ice water; let cool. Peel eggs under running water; halve lengthwise.
Place pickled vegetables individually in small serving bowls. Place olives, almonds, and some sea salt each in a small bowl. Place eggs on a platter and serve with sauce, pickles, olives, almonds, and sea salt. Let guests assemble eggs as desired.