Two entries with the name Budicius.
Biducus, Budec, Budes, Budiz, Dubricius, Pudentius
The king of Brittany who received Uther and Ambrosius’s children, when they fled Britain in fear of Vortigern. Budec sheltered them in his realm until they had come of age and were ready to retake Britain from Vortigern.
His son, Hoel, ruled after him, which, most probably, makes him identical with Budicius below.
There may be a confused memory here of King Budic I of Cornouaille (in Brittany) who traditionally regined before AD 530.
Agricola | The Legend of King Arthur
Historia Regum Britanniae | Geoffrey of Monmouth, c. 1138
Roman de Brut | Wace, c. 1155
Brut | Layamon, late 12th century to mid-13th century