I'm on cricket wireless as well and i haven't been on any cricket branded phones until now. That means no VVM. You could try a third party VVM provider called YouMail.
Do you have any insight into why CricKet VVM is "special" when compared to the other carriers? From what I understand, most other carriers are natively supported by WP/W10M. Is it an issue on Microsoft's side or on ATT/CricKet's side? I'd really like to see VVM support, but not at the cost of being on grossly outdated firmware.
I think I'm just going to de-brand my Lumia 635 to the NA Variant, get the firmware, go back to W10M Fast Ring, and be "happy" as I can on this device. I think a Lumia 735 or 640 are in my future...
Edit:
I've nearly completed the de-brand to the NA variant, but I can't get the thor2 command to execute properly as it says that -skipflash is not a supported command. It looks like perhaps the syntax has been changed and it is now -skip_flash. Is that correct?
I can't believe the NA variant doesn't have GDR2 still. Wow. Is there a single ROM that is actually fully up to date for this device?
I've attached a screenshot of the console output if that would be helpful.
Edit 2:
After updating the product code with thor2, the Windows Device Recovery Tool saw that the server had updated firmware and OS version compared to what was on the phone, despite the fact that I had checked multiple times for updates after I had changed the registry values and had found no updates. Really odd. Glad I performed that last step!