@Natanox @anopka @dansup @Chocobozzz to illustrate the multicast concept and how it can reduce the resource load I recommend this Introductory talk. It covers IoT updates but illustrates the idea.
https://archive.fosdem.org/2020/schedule/event/iotmulticast/
Although I do caveat that while multicast can help, you are better designing with multicast in mind in the first place.
As we found when we did a unicast version of the updater to test unicast v multicast.