It isn't used like a vowel. There's no word 'XwY' for any string of letters X,Y - and you can't prounounce 'xwy' (for any single letters x,y) without adding vowel sound.
E.g., (spelling vs pronunciation) 'town' vs 'toun', 'own' vs 'oan', 'bow' vs 'bo' or 'bau', etc.
It definitely seems like the most vowel-like consonant after 'y'.
Awe, ewe, owe, awl, owl, own, two...
But my point was that in all other European languages, the letter 'W' is clearly a consonant, usually realized as [v] or [ʋ], and seen as a variant of 'V'.
English is the odd one out, English sees it as a variant of 'U', and it's not clearly a consonant, it's a semi-vowel as you pointed out further down.
It varies across the v <-> w spectrum depending on region, and also some words seem mostly nearer one or the other (but it's the same character, there isn't a second).
You sometimes hear that in native speaker's English, but more 'v's sounding nearer a 'w' than the other way around (as in native German speakers).
Fascinating how growing up with different languages teach us different sounds, and those we didn't use can be so difficult to produce, even if we can hear and understand the difference.
I struggle with two things in Hindi: aspiration (transliterated as 'ta' vs 'tha' for example, but that's not an English 'th', it's 'ta' with air forced out) which I usually either don't pronounce clearly, or it's way over-exaggerated; and retroflex consonants, which I can hear but often struggle to pronounce correctly quickly enough to flow with the rest of the word. And particularly 'd.a' which when correctly pronounced contains (to my ear) some 'r'.
For those that don't know.
It was nice to read it once again...