cashu.me is still far from being NIP-60 ready. There are code bases you can have a look at, probably the simplest one being nutsack.me - nostr:nprofile1qqs04xzt6ldm9qhs0ctw0t58kf4z57umjzmjg6jywu0seadwtqqc75sprfmhxue69uhhq7tjv9kkjepwve5kzar2v9nzucm0d5hsz9thwden5te0wfjkccte9ejxzmt4wvhxjme0qythwumn8ghj7un9d3shjtnswf5k6ctv9ehx2ap0y8qdrm's NDK will/does support NIP-60 wallets afaik. We use NDK in cashu.me as well.