What technical methods can be implemented to force Nextcloud Pi users from sharing authentication credentials? For example, In the military, this is halted with a certificates held in a smartchip in the ID (CAC) card. Ideally users would have discentive to share a credential: credential resuse (FB / Google).
Update: Maybe EMV (Chip and PIN) can be used as part of 2-factor authentication: I suspect most people not want to loan out their bank card.
Any edits to sharpen (reduce the scope) of the question is appreciated.