Born in Ypané in the Central department, Viera began playing football in the Cerro Porteño academy.[2] In May 2020, the 18-year-old signed his first professional contract.[3]
On 17 February 2023, starting by surprise away to Guaireña on the debut of new manager Facundo Sava, Viera scored his first goal for Cerro Porteño with a left-footed strike in a 2–0 win.[7] In April, his sudden absence against Sportivo Ameliano caused rumours that the Argentine had dropped him, but he was in fact hospitalised after having been kicked in the genitals during the previous match against Tacuary.[8] His contract was extended in June, to last through 2026.[9]
Viera rejected a move to SC Internacional of the Campeonato Brasileiro Série A in 2023. In February 2024, his agent Renato Bittar said that he would likely leave for another Brazilian club in the middle of the year.[10]
International career
Viera was captain of Paraguay at under-15 and under-17 level.[2] In the latter team, he helped them to the quarter finals of the 2019 FIFA U-17 World Cup in Brazil, giving two assists as they came from behind to beat neighbours Argentina 3–2 in the last 16; Spanish sports newspaper Marca named him one of eight stars of the round.[11]