In some previous threads the api was working (latest december 2019). In may 2020 it's not working again and there is nothing about live_chat not working on mobile in the documentation here: https://support.google.com/youtube/answer/2524549?hl=en . On web you can embed and the comments are shown correctly on the page
From what I have found there is currently no way to embed YouTube chat on Mobile. The ways that I have found in the past look to be patched and no longer are supported or work.