I have a new Pixel 5a5g from Google Fi, not made for Verizon/Visible. It's not "supported" because it lacks mmWave 5G. It works fine and, since there's no mmWave anywhere near me, that issue is moot.
My Google Fi line uses the eSIM and my Visible SIM is in the physical slot. Google Fi is default for voice and text and wifi calling is enabled. Its mobile data is turned off.
Visible is default for data. I'm told Fi will use the Visible data connection for wifi calling in the the absence of a wifi connection.
The Visible SIM was activated in a ZTE Blade and that's what shows in my Visible account. It works fine in the Pixel. I tested voice and text, too.
Is there any need to change something so the Pixel shows up? Activation? Is there any reason not to? Since it's an "unsupported" phone, is that even possible?