Meshtastic is one packet, Reticulum is like TCP/IP replacement, it can split message into multiple packets.
BTW Reticulum is not limited to LoRA. But it works over LoRA, seamless splitting of packets and then reassembling.
Reticulum needs a more performant machine, the ESP32 is only radio interface. So encryption, packet assembly and reassembly is happening outside of the ESP32.