>>rodlet+gb
Fwiw, I've seen users suggest hybrid approaches. Interestingly it could reduce some of the costs they list here and looks like a route one could take to slowly build towards a fully or hybrid federated system instead of jumping straight there. But I am unsure how much the community likes the idea and judging by that last post it doesn't seem like the mods do. But this one takes note as two users were willing to place a bounty on the feature request
https://community.signalusers.org/t/signal-airdrop/37402