Place green beans in a large pot and cover with salted water; bring to a boil. Reduce heat to medium-low and simmer until tender yet firm to the bite, about 5 minutes. Drain.
Cook and stir red bell pepper and onion in a large nonstick skillet until tender, about 5 minutes. Add mushrooms; cook for 3 to 4 minutes.
While mushrooms are cooking, drain and rinse noodles; set aside.
Combine almond milk, cream cheese, seafood seasoning, garlic powder, and pepper in a blender; blend until smooth.
Add greens beans, noodles, cream cheese mixture, and tuna to the mushroom mixture. Stir gently until heated through, 5 to 8 minutes.
