Wenn ich mich richtig erinnere kann man in FF mittlerweile auch mit der Maus in ner PDF kritzeln, damit müsste also auch unterschreiben (sehr rudimentär) gehen.

Hmm, afaik florisboard doesn’t support word suggestions at all right now. You can read up on it a bit on github but to make it short: the main dev is struggling with creating his own performant word suggestion algorithm.

Do you mean different characters/local keyboards, or different dictionaries?