Hello, I’ve just switched to a Google Pixel 4 without realising that it doesn’t have native ANT+. I’m trying to broadcast my HR to Zwift Android from Garmin 645 Music.
I have a USB-C to USB adaptor that came with phone. Do I just have to buy any ANT+ USB dongle and connect to the phone via the adaptor?
I see there are a variety of ANT+ plugins available to install on Play Store. I assume I’ll need one of these as well?
The Pixel 4 does not have native ANT+ support. Some (all?) Samsung phones do, and it works nicely, using those plugins you mentioned.
So your only option is to utilize the Pixel’s OTG support, hooking up external ANT+ dongle - but I am unsure if your adapter is the one to use (an OTG cable is a bit different than the standard one)
To your question: “Yes” + additional cable 
Before you start spending money on a fix, I’d recommend looking at Bluetooth chest strap HRMs.
They are more accurate, stay in position better when cycling and would connect natively to your pixel.
I gave up on my vivoactive 3 music watch as a HRM. It was ok for running but a nightmare for cycling. The way you grip the handlebars and move into positions causes an air gap between wrist and optical sensor.
I went for a Garmin dual HRM in the end and it is far more consistent, never misses a beat
Thanks for the replies.
I’ll look into the OTG option. I’m using Zwift for running so wrist-based HRM works perfectly.
I’ve got this working now. Dug out an old ANT+ dongle and connected to the OTG adaptor supplied with the phone.
Installed the ANT+ demo app which then guides you through which plugins need to be installed.