They haven't exactly been secretive about it, here is Vizio CTO giving an interview at CES this year over the topic https://www.theverge.com/2019/1/7/18172397/

They haven't exactly been secretive about it, here is Vizio CTO giving an interview at CES this year over the topic https://www.theverge.com/2019/1/7/18172397/airplay-2-homekit-vizio-tv-bill-baxter-interview-vergecast-ces-2019 https://www.theverge.com/2019/1/7/18172397/airplay-2-homekit... Meat of it starts @15:58