It looks like cryptocurrency related packages are ending up in one of two places: net-misc or net-p2p. The latter seems to be by virtue of the fact that, as an implementation detail, most cryptocurrency networks are peer-to-peer in nature.
A (very) cursory look at the Gentoo ebuild repository shows: net-misc/bfgminer net-misc/electron-cash net-misc/electrum net-misc/electrum-ltc net-p2p/bitcoin-cli net-p2p/bitcoind net-p2p/bitcoin-qt net-p2p/litecoind There are probably more, but this is what I could find quickly and easily. Wouldn't it make more sense to silo these ebuilds (and similar) under something like fintech instead? ~Jeff