LoRa is designed to handle hundreds of devices in the same area since the commercial use case is densely deployed nodes. The spreading factor is orthogonal so it is able to multiplex in the same frequency assuming your data rate is constrained enough for the largest spread factor.

There's a bit more on involved with gateways and coordination that you don't get in P2P mode but the PHY has the pieces you need I'd you wanted to do something similar.