Welcome to the community! The goTenna Mesh device pairs via Bluetooth with just one phone at a time. So in the use case that you describe, each goTenna Mesh would only be able to be paired to one person’s phone in each group. While the members of the group could “share” the goTenna Mesh device, that would require unpairing and repairing each time it is handed off between group members. So from a practical standpoint, if all group members want to text at the same time, each group member needs their own goTenna Mesh device.
The max range between phone and goTenna Mesh device varies, but considering that it’s Bluetooth, you can usually expect good reliability for distances of under 100 feet.
As to the question of range between goTenna Mesh devices, (which use radio transmissions in the 900Mhz frequency band), results are highly variable. Factors affecting the range of a 1 hop transmission include terrain, foliage, buildings, and weather conditions. In the best of situations, where there is perfect weather and no obstructions between the sending and receiving units, users have reported 1 hop transmissions of as much as 50 miles. In the worst of conditions, where there is no direct line of sight (i.e., hilly terrain, forestation, city buildings, etc.) and the weather is poor, 1 hop transmission range may be well under 1 mile. Most of the time, you can expect that 1 hop transmissions will have a few miles of range in average conditions.
The beauty of the goTenna Mesh device is that the messages you send can “hop” multiple times if more than 1 sequential transmission is required to get to the intended recipient. By design, the message can automatically transmit up to 3 hops before it stops - and if you subscribe to the goTenna Plus service, that is doubled to up to 6 automatic hops. That gives you a much better likelihood of successful receipt than a single point to point transmission.