I have the same a Pixel 3 recently upgraded to Android 10. It worked perfectly prior to the upgrade. But now won't even open. I have uninstalled and reinstalled. I have no intention of doing a factory reset as everything else works perfectly. I suspect that Virgin have not managed to make the app compatible with Andorid 10, it's not like they didn't know it was coming, but they probably won't fix it until other phones get upgraded and stop working as well. Once enough people complain it may get fixed. Poor standards of development though.
I just tried to use the Go app on my Pixel 3XL for the first time since upgrading to Android 10 and I'm getting the same behaviour as everyone else in this thread. It just shuts down before I can do anything.
I really don't want to do a factory reset on my phone, so I'm just going to have to wait until VM fix the bug. Is there any news on that?