Yes, 'son' and 'sun' are homophones in all varieties of English.

In standard English, they're both pronounced /sʌn/.

An example of a non-standard accent is that of the north of England, where many speakers don't have the /ʌ/ phoneme. A native speaker from Manchester, for example, might pronounce both words as /sʊn/, with the same vowel as 'put' or 'book' . This is different from standard English, but 'son' and 'sun' would still be homophones.