Domelch o Gwynedd verch Maelgwyn - Domelch

She has been suggested to be pictish, not welsh:

..."It has been suggested that Gartnait son of Áedán could be the same person as Gartnait son of Domelch, king of the Picts, whose death is reported in about 601, but this rests on the idea of Pictish matriliny, which has been criticised. Even less certainly, it has been argued that Gartnait's successor in the Pictish king-lists, Nechtan, was his grandson and thus Áedán's great-grandson.

Of Áedán's daughters, only one can be plausibly named. This is Maithgemm, or Gemma, who married a prince named Cairell of the Dál Fiatach. The names of Áedán's wives are not known, but one was said to be British and another may have been a Pictish princess named Domelch, if indeed the Gartnait son of Domelch and Gartnait son of Áedán are one and the same."...

"https://dlab.epfl.ch/wikispeedia/wpcd/wp/%25/%25C3%2581ed%25C3%25A1...;