I like this metaphor.
Spanish ñ, Catalan or French ç, German ß. Similarly for ł and other Polish letters. It seems strictly speaking the latin alphabet cannot cover many european languages. But mostly we can say latin can express that. You can write "ss" for German and l for Polish, etc, so it can definitely be used. Source: whatssap messages.
Spanish: 'ny' as a digraph. Accented vowels (stress marks) and ü -> 'a 'e 'i 'o 'u and maybe :u.