non-pangram: 819
pangram: 132
perfect pangram: 49

def classify_string(s: str) -> str:
    alphabet = set("azertyuiopqsdfghjklmwxcvbn")
    input_filter_lower = [c.lower() for c in s if c.isalpha()]
    input_set = set(input_filter_lower)

    if not alphabet.issubset(input_set):
        return "non-pangram"
    return "perfect pangram" if len(input_filter_lower) == 26 else "pangram"

if __name__ == "__main__":
    for k, v in {k: sum(classify_string(s)==k for s in open("List of 1000 strings.json").read().splitlines()[1:-1]) for k in ["non-pangram","pangram","perfect pangram"]}.items():
        print(f"{k}: {v}")

Tried my best to write my code as short as possible with keeping it still be readable.
A nice quick challenge to wake up my coding skills.

non-pangram: 819
pangram: 132
perfect pangram: 49

def classify_string(s: str) -> str:
    input_filter_lower = [c.lower() for c in s if c.isalpha()]
    if len(set(input_filter_lower)) != 26:
        return "non-pangram"
    return "perfect pangram" if len(input_filter_lower) == 26 else "pangram"

if __name__ == "__main__":
    for k, v in {k: sum(classify_string(s)==k for s in open("List of 1000 strings.json").read().splitlines()[1:-1]) for k in ["non-pangram","pangram","perfect pangram"]}.items():
        print(f"{k}: {v}")

Tried my best to write my code as short as possible with keeping it still be readable.
A nice quick challenge to wake up my coding skills.