While I read Nana or Nanna? (When Referring to Grandmother) in wikitionary it also means one's grandmother https://en.wiktionary.org/wiki/Nana, it doesn't tell whether it means grandmother from father's or mothers side or it doesn't matter ?
Among Germanic languages, only the Scandinavian tongues make a distinction between maternal and paternal grandparents, conveniently doing so with compounds: mormor, lit. mothermother, is a maternal grandmother and farmor, lit. fathermother, a paternal one.
For grandmother, both German and English originally prefixed mother with old(er): OE ældmoder, ME eldmoder; Low German Eldermutter, Ellermutter, but under the influence of French grand mére, became grandmother and Großmutter. In German, the French for aunt and uncle also supplanted terms that originally made a distinction between paternal and maternal.
Since English has never made a distinction between maternal and paternal grandparents, less formal terms such as nan/nanna will not do so either. Gran, for instance, was my paternal grandfather, but many people call their grandmothers that. To my cousins (father's brother's children) he was Papa, and their mother's mother was Nanna. How these names or nicknames are used varies from family to family with no general lexical agreement.