I also see nothing wrong with 'he was bought a smartphone'. 'Somebody bought him a smartphone for him' (the active voice sentence) has two objects - direct and indirect. There are therefore two ways to make it passive - A smartphone was bought for him and He was bought a smartphone. This is pretty normal when a verb has both direct and indirect objects. Her company gave her a raise - She was given a raise / A raise was given to her. Somebody sent an email to me - I was sent an email / An email was sent to me.

Personally I find "he was bought a smartphone" entirely grammatical. Sorry if that confuses things!

You would never use the passive 'He was bought a cellphone.' Instead we would say: he was given a cellphone. Generally, you simply have to get to know which verbs can be used in the passive and which not. As far as I know, there is no 'list' or rule.