Alphabets Including a Particular Letter
Using Alphabet and the list of entities of "Alphabet" type, it is easy to find which alphabets contain a particular letter.
Try to find which ones have the letters ø, æ, ñ, or и.
In[1]:=
alphabetEntities = EntityList["Alphabet"];In[2]:=
Select[alphabetEntities, MemberQ[Alphabet[#], "ø"] &]Out[2]=
In[3]:=
Select[alphabetEntities, MemberQ[Alphabet[#], "æ"] &]Out[3]=
In[4]:=
Select[alphabetEntities, MemberQ[Alphabet[#], "ñ"] &]Out[4]=

In[5]:=
Select[alphabetEntities, MemberQ[Alphabet[#], "и"] &]Out[5]=

Get variants of the vowel o using AlphabeticOrder.
In[6]:=

lettersO =
Select[CharacterRange[1, 65535],
AlphabeticOrder["o", #, IgnoreDiacritics -> True,
IgnoreCase -> False] == 0 &]Out[6]=
Build a function to extract which languages contain a particular letter.
In[7]:=

alphabets = Alphabet /@ alphabetEntities;
getAlphabet[letter_] :=
Pick[alphabetEntities, MemberQ[#, letter] & /@ alphabets];Show the o vowel variants and their alphabets.
show complete Wolfram Language input
Out[8]=
