NOUN1でもNOUN2でも as “whether it’s N1 or N2/including N1 and N2”
This grammar pattern is used to express that a statement still applies whether it involves a certain noun, NOUN1, or a certain other noun, NOUN2. In other words, it is used to provide examples for the statement. There does not have to be only two NOUNs used in this pattern (i.e. there can be more than two NOUNs used together in this construction). The implication that complements this grammar pattern is that NOUN1 and NOUN2 are simply examples and are probably not the only examples that apply to the statement; as such, 何でも is sometimes used as the “final listed NOUN” to denote this continuity.
Kono eiga wa, otona demo kodomo demo tanoshimeru.
(Whether it’s adults or kids, anyone can enjoy this movie.)
Bunpou demo kanji demo, nihongo no benkyou wa taihen desu.
(Whether it’s the grammar or the kanji, studying Japanese really is quite difficult.)
Ano restaurant wa, nihon ryouri demo America ryouri demo Italy ryouri demo, nandemo aru.
(Whether it’s Japanese cuisine, American cuisine, Italian cuisine, or anything else, that restaurant has everything.)