Moto g6 for at&t go phone

Assuming that the phone is the unlocked model, and the existing SIM fits in it, it should work.  You probably want to ensure you are on a compatible plan that supports data, or disable data on the phone.

I purchased an unlocked Motorola Moto G6 in July 2018. Love the phone 🙂 I had an ATT Windows 8.1 GoPhone Nokia Lumia 635 before that. My ATT plan is the $1 daily plan. I don't use data, only WiFi and rarely make phone calls due to having a weak to non-existent signal in my home.
On July 17, the ATT store put a nano-SIM card into the new phone because the old SIM card was too large. All was well, until I got home and noticed that my account began deducting 1 cent 5KB "data" every 4 hours from my prepaid balance.
12 days, dozens of e-mails and screenshots, 3 customer reps and 1 advanced tech rep later the charges continue!!
From the very start, I disabled ALL data, EVERYWHERE on the phone, from every single App, background data, notifications, even the location satellite ping, and I tested airplane mode too. Nothing helps! The phone keeps charging my account, except when I switch it off completely or remove the SIM card. ATT advanced tech rep was unable to disable or block data function from their end. All reps were nice, said they had never seen anything like this, and reimbursed or even added funds to my balance. I've spent hours researching forums, because this has been happening for years with ATT prepaid accounts. It did not happen with my ATT GoPhone though, which was a smartphone too. But something with Motorola and ATT is triggering that auto-charge. Any posts marked as "Solved" in regard to the "auto-charge" issue, really aren't solved, because posts about this problem appear year after year. 
I'm fed up now. I keep the SIM card out of the phone and only put it back in when I need to make a phone call, which is rare. I use the phone 99.9% with WiFi, so now I'm researching and waiting to find an ideal WiFi phone service that will let me keep my number of 23 years (ideal) and will allow me to free myself from ATT or any other cell phone carrier.
Time will tell - so far, no WiFi phone service has been able to cover all of the wants and needs - I researched them all. Facebook Messenger is a logical choice for right now, but many of my family/friends are not on FB. I'll test Google Hangouts too. Skype, which I've been using via desktop for the last 15 years, is now being completely destroyed by Microsoft - so that option will soon be a dead end. And even if switching to a TING no data "plan", who guarantees that my phone won't continue to auto-charge from that mysterious source nobody can seem to find?
I'm in no hurry - the SIM-card-less phone works fine for me. No spam calls to deal with, and everyone knows, how to reach me via other ways. Meanwhile, I'll keep the prepaid plan alive in order to keep my number alive. Just wanted you to know, in case you experience mysterious auto-charges too.