Generally speaking it's better to bring grass to your tort and not the other way round
The risk of escape when they're not in a secure enclosure is high... No matter how much you say it won't happen, we have had far too many escapes reported on here by owners who were only distracted for a moment.
You need a pesticide and herbicide free area. You also don't want it to be anywhere dogs are exercised as dogs regard torts as chew toys and torts frequently regard dog poop as dinner... the risk of your tort ingesting parasites is high if you are in a community area like a park.
At one year old they're probably a bit small for outdoor time yet. They need to stay in the warmth and humidity of their enclosure.
Have you read the TFO care guides for Sulcatas?
They're written by species experts working hard to correct the outdated information widely available on the internet and from pet stores and, sadly, from some breeders and vets too.
This is why we think it's best to have a nice yard where you live (so you don't have to "take" him anywhere, you just set him up in a safe outdoor area and he grazes to his heart's content)