In order to send a datagram to multiple IP the first, and naive idea, one can think of is to change the datagram protocol to allow for multiple destination. Today, 2020, is the right time. I am thinking about platforms that have hundred or thousand of simultaneous receiving ends, so that the branching point occurs near the destination. Again, googling this proposal is not new (1) RFC 1770, category informational.

Edited: It seem that RtcDataChannel can be used with SFU, example LiveSwitch in 2018, but they don't use multiple destination datagrams (3)

More on similar proposal (2).

(1) IPv4 Option for Sender Directed Multi-Destination Delivery. The Selective Directed Broadcast Mode (SDBM) is an integral part of the U.S. Army standard for tactical data communication networks as defined in MIL-STD-188-220().

(2) https://www.researchgate.net/publication/238663190_IPv4_Opti...

(3) https://www.frozenmountain.com/developers/blog/archive/indus...