Graham Robb, in his travel account France: An Adventure History, London: Picador, 2022, revives the ancient theory of the Lake of Sarliève (south-east of Clermont, surmounted by Gergovia) as the location of Avitacum (part 1, ch. 2 ‘A Home in Gaul’). Cf. Stevens 1933, 187-88, Trément 2007.
Link to the catalogue here