Oh sorry, can’t think of an easy solution then. I’ve seen that audiobookshelf can find metadata for you, that could be doable. They also support ebooks but if I understood correctly from their docs they don’t get synced to the audio position, just to themselves.
A promising but still in beta software is Storyteller, under very active development here. It works by creating a ‘rich’ epub that contains the audio synced line by line, which you can then read/listen to with just one app.
There’s also older software with a similar approach like syncabook but at a glance it seems less usable than Storyteller.
Blxter