Re: Official PDFs from Nintendo's websites.
This page, from the portuguese Nintendo website, has 19 Nintendo 64 game manuals.
Searching for 'website:nintendo-europe.com filetype:pdf' yelds a lot of results.
While it may not seem like it, nintendo-europe.com is an official Nintendo website. In fact, https://www.nintendo.com/regionselector/ has a list of official regional websites. The polish one is in the domain nintendo-europe.com.
Dokey Kong 64 (source pdf, not a scan)
The Legend of Zelda: Ocarina of Time (hi-res scan)
Forgot to mention: since there are official nintendo websites hosted at different domains, for a thorough search, one would have to also try all of them, such as nintendo.co.jp, nintendo.de, nintendo.ca etc.
This website has a list of official nintendo websites, but I'm not sure if it has all of them: https://nintendo.fandom.com/wiki/List_of_Nintendo_websites