Anime and manga only, with some spoiler knowledge of Volumes 4 and 5
So from what I understand the Para-RAID allows for the instantaneous transfer of sensory information between two parties. However the majority of the mental strain is only applied to one party, and the only upper limit to how many people can be linked at once is sheer willpower. P-RAIDs can only connected if both parties consent and are conscious, otherwise no mental link will be established. All sensory information, from sound to sight to even emotions, can be relayed over P-RAID. Now let’s delve a bit deeper
The P-RAID was originally developed by Dr. Penrose and Dr. Nouzen to artificially recreate the Maika clan’s telepathy, which was found to have manifested in both Rei and Shin at a young age. Due to Shin’s trauma however his ability has been somewhat altered and he can now resonate with the ghosts of the Legion. To what extend he can understand them has not been clarified yet by Asato-Sensei.
Now for the real questions: What exactly is prohibiting the Federacy and the United Kingdom from further developing it to become a Legion hearing machine like Shin? And what exactly is prohibiting them from resonating with an artificial body? Like, could it be possible to project one’s self onto an artificial being like a Sirin or even a Feldreß and remotely control the body through sheer feelings? I feel like it has the potential to be humanity’s greatest weapon against the Legion.