Marlinski

https://www.rfc-editor.org/rfc/rfc4838

It makes no sense to use a protocol where the source is the one responsible for taking care of retransmission when the network spans accross minutes/hours of delay.

I worked the field both academic and startup, I even made one of the first implementation of the Bundle protocol for store carry and forward (IETF transport protocol for the deep space network RFC9171).

Turns out the Mobile OS are making this kind of communication nearly impossible. To work well, it basically needs background job (automatic scan of nearby ble/wifi/radio) and automatic connection without user interaction (imagine being prompted to accept a connection every time you pass by someone), both have been basically made impossible (especially after covid).