Tamil: 247
🇰🇭 Khmer: 74
🇳🇵 Nepali: 64
🇮🇳 Hindi: 52
🇯🇵 Japanese: 46
🇵🇰 Urdu: 36
🇦🇲 Armenian: 36
🇷🇺 Russian: 33
🇮🇷 Persian: 32
🇹🇷 Turkish: 29
🇪🇸 Spanish: 27
🇬🇧 English: 26
🇩🇪 German: 26
🇫🇷 French: 26
🇵🇹 Portuguese: 26
🇰🇷 Korean: 24
🇮🇱 Hebrew: 22
🇮🇹 Italian: 21
🇵🇬 Rotokas: 12
Note: The German alphabet consists 26 regular letters, 3 „Umlauts“ (mutated vowels: ä, ö, ü) and 1 ligation (double letter: ß - spoke as a „sharp s“).
It probably doesn’t count as a shower thought. Also, the list is probably all wrong, e.g. Khmer and Tamil are abugidas, not alphabets.