Can the modal verb "can" be pronounced as /ŋ(k)/?

Yes, it exists but more prominently when the modal, preposition or any word is unstressed and takes a schwa sound (ə). It has the ability to transform to [ŋ] as a bridge to the K in the next word. This is because there is resistance to articulate the consonant n if your following word is more strongly stressed (a nasal is a closer bridge to a glottal stop and the schwa sound invites it for linking purposes). . If you stress the modal 'can' [kæn] the [ŋ] disappears. I notice the same effect with unstressed prepositions eg "in Canada." and relative pronouns eg "when crying...".