I've exaustively searched for working ADB and FASTBOOT for ARM64 (Android), but only found suspect files, broken links, non-working servers and so on.
I need this because I'm on DeX right now, and would like to ditch my Windows notebook. But the only thing I can't do from an Android phone right now is... flashing another Android phone. Not without these tools and supporting libraries.
It's a pity that Google removed them from Android since Marshmallow.