We have total control over Switches so with that in place it is the same as any other system. Some of the earlier hacks will transparently replace files but I would not suggest that for this and instead just do plain old file replacement and a custom ROM.
So the main two formats for Switch games are NSP and XCI, though the latter is mainly the domain of the SXOS crowd right now and the free custom firmwares are a bit touchy about including it for reasons only care to contemplate (they say piracy but eh).
I have some documentation aimed at the GBA and DS
Afraid I don't have any nice intros in Hungarian right now. You might find some out there. I tapped in magyar ROM moddolásához, hackeléséhez and ROM hackeit into a search and got a few results but don't speak Hungarian anywhere near well enough to comment on the quality of the contents. There are also a few translations for older systems ( http://www.romhacking.net/?page=tra...=50&order=&dir=&title=&author=&transsearch=Go
lists several) so you might be able to find more from the authors there.
The Hungarian alphabet is quite a bit larger than the standard Roman alphabet. This means you might run into trouble there compared to some other European languages which only have two or three more characters than those used in English. It is not the worst thing in the world but I have not checked what goes for Switch fonts at this point, and I don't know if anybody has.
For unpacking Switch games in general I think we are still suggesting hactool ( https://github.com/SciresM/hactool
). There might be others people like more out there now though. The Switch does not have great emulators right now but emulators are more nice than essential here.