Not GoPro, but Norwegian broadcaster NRK have filmed several train journeys as part of their "slow tv" offering. Original HD video files (200++ GB) are available [0], and there are multiple versions on Youtube, like a 10 hour trip with Nordlandsbanen from Trondheim to Bodø [1] and a 7 hour trip from Bergen to Oslo [2], including a 10 minute stretch from Finse where the scenes from Hoth in Star Wars Episode V: The Empire Strikes Back were filmed [3].
[0] https://nrkbeta.no/2009/12/18/bergensbanen-eng/
[1] https://www.youtube.com/watch?v=831Drz4YQdQ