Welsh Polytheism could fall under Brttonic Polytheism. It can also be its own thing.
The Welsh were a group of people living in Wales that split from the Brittonic peoples.
Many Brythonic territories fell under Anglo-Saxon control after the Anglo-Saxon invasion of Britain; however, Brythonic Celtic religion was largely preserved in Wales. Since several Welsh myths were later Christianized, determining if the characters were actually gods, mortals, or historical figures may be challenging.
Welsh Gods and Goddesses
Gofannon – A Smithing God.
Ceridwen – A goddess of rebirth and transformation.
Amaethon – god of agriculture
Creiddylad – goddess of flowers and love
Gwydion – magician, trickster, and hero.
Agrona – goddess of the river Ayr, and of war and slaughter
Arawn (Arawen) – king of the otherworld realm of Annwn
Branwen – goddess of love and beauty
Welsh Myths and Stories
The Four Ancient Books of Wales – https://tinyurl.com/4ya2pax4
The Mabinogion – https://tinyurl.com/4wsudyxa