Coptic
Coptic keyboard layout
Coptic uses the Greek alphabet for the majority of the letters. Due to this, in Unicode 3.x?, Coptic letters appear in the Greek&Coptic Unicode block. That is, most of the letters are shared with Greek. In practice this was not useful, as the Coptic audience has specific preference on how the typeface should look like. In particular, for a Greek person, Coptic fonts look like Byzantine (liturgical) letters found on icons.
Since Unicode 4.1, Coptic has its own Unicode block. While Greek has precomposed letters (codepoints for individual letters but codepoints also for each variation with accent marks), Coptic in Unicode 4.1 does not. It is achievable to
Existing Coptic use (AFAIK) does not use Unicode while there are attempts to start using Unicode. For some contacts, see Coptic Church.
There are several Coptic Unicode fonts available here: [1].
There exist Coptic Unicode 4.1 fonts, one of which has a FLOSS license and is already in the Debian repositories.
The issue is with the keyboard layout. To the best of my knowledge there is no Coptic Linux keyboard for Unicode 4.1 Coptic.