I store mine in KeePassXC, when transfering between machine I use Syncthing over Wireguard, sometimes Age File Encryption and Web Wormhole. (just don't sync the key file).

I locked the key file with gocryptfs.

nostr:nevent1qvzqqqqqqypzqdr6ydcfqrgeknj82c3pt98ghknsdtju0pw7p8jeu3s9lydq8ayuqqsx7qs46cll9jmrzh67mcl4qcha9sygzgsex8czqpnfkdjaa6yn4tggy0z3v