If the NixOS team cannot handle this then I question their capabilities. This is cake work.
A half petabyte at other places such as wasabi would cost 35k a year, including bandwidth.
Open street maps by comparison in 196GB compressed including full history. 20 years of full snapshots would amount to only .2PB, or 20k a month to host on cheaper storage providers.
I don't think using OSM's budget was the best example.