Is the word nono the same in Brazilian and European Portuguese?

Yes

The word "nono" is identical in spelling, meaning, and grammatical function in both Brazilian and Continental Portuguese, as it is the masculine ordinal number for "nine" (9th). The only difference lies in pronunciation: in Brazilian Portuguese, the unstressed final "o" is typically pronounced as a clear [u] sound, whereas in Continental Portuguese, the final "o" is much more reduced and closed, often sounding nearly silent or as a very short, muffled vowel.

Brazilian Portuguese

1. O nono aluno da fila é meu irmão. (The ninth student in line is my brother.)
2. Ele mora no nono andar. (He lives on the ninth floor.)
3. Este é o nono dia de chuva. (This is the ninth day of rain.)
4. O nono capítulo é o mais emocionante. (The ninth chapter is the most exciting.)
5. Ele terminou em nono lugar na corrida. (He finished in ninth place in the race.)

Continental Portuguese

1. O nono aluno da fila é o meu irmão. (The ninth student in line is my brother.)
2. Ele mora no nono andar. (He lives on the ninth floor.)
3. Este é o nono dia de chuva. (This is the ninth day of rain.)
4. O nono capítulo é o mais emocionante. (The ninth chapter is the most exciting.)
5. Ele ficou em nono lugar na competição. (He finished in ninth place in the competition.)