Make sure you have at least 40GB of free space…
That's a lotta space. is that for the Bitcoin part or or the Bitcoin+Nix part or Just the NIX alone?
Nix in general is disk heavy for larger projects because it hashes every dependency all the way down for each thing. So if you, for example, depend on Fedimint 0.1.3 in part and then some other package depends on 0.1.1. You’ll have the binaries for both of those. This is my first time attempting to explain nix so I hope that’s clear as mud.