I thought Id share a list of Australian glass suppliers that appear to supply one-way mirror glass (I am sure there are lots more, but this is what I found in Google).
FYI I have emailed a couple and are yet to hear back, but YMMV. If they receive multiple enquiries they may be more likely to start supplying this type of glass in the small sizes required for smart mirrors.
greaterglass.com.au/glass/two-way-observa/
chevronglass.com.au/stocked-substances/
walshsglass.com.au/view/mirrors
Seems I cant paste the full list here - keeps getting flagged as spam.
Full list here: https://forums.whirlpool.net.au/forum-replies.cfm?t=2571313#r11