Bring sugar, 1/2 cup cherries, and 1 1/2 cups water to a simmer in a small saucepan over medium-low heat. Cook, stirring often and mashing fruit, until cherries start to fall apart, 15–20 minutes. Add remaining 1/4 cup cherries and cook, stirring, until plumped, 5–8 minutes. Let cool. Cover and chill if making ahead (up to 1 week), but bring to room temperature before serving. Preheat oven to 350°. Toast almonds on a rimmed baking sheet, tossing once, until golden brown, 5–7 minutes. Let cool. Combine milk, barley, and salt in a medium saucepan. Scrape in vanilla seeds and add pod. Bring to a boil; reduce heat and simmer, stirring often and adding a little water if mixture gets too thick before barley is cooked, until barley is very tender and porridge is the consistency of oatmeal, 40–50 minutes. Add white chocolate and sugar off heat, stirring to melt chocolate and dis– solve sugar. Let cool. Remove vanilla pod. Whisk cream in a large bowl to soft peaks. Fold into porridge in 2 additions; stir in half of almonds. Serve topped with compote and remaining almonds.