I’ve been using the Android version for quite a while now, on various tablets.
Sometimes I’ll cast it to the TV over wifi, which works quite well, only a slight delay.
I do have a PC for Zwift as well, and with an upgrade yesterday it runs Zwift well in Ultra. Yes, it looks much better on the PC (now), but I find the tablet more convenient, as I have a DIY stand for it within easy reach.
The PC is really just for races, when a Bluetooth dropout might cause things to be flung out of windows - I do get the occasional power sensor dropout with the Android version, so ANT+ on the PC works better for me there.
I did use it with my phone once, as a workaround for some issue on my tablet at the time, and it ran fine, but the small screen and an issue with the specific phone and casting to the TV made it a poor experience. With a better phone, or a USB-C to HDMI cable your experience would probably be better.