frost2x has NIP-44 integrated. Bifrost nodes construct the shared secret, then pass it into NIP-44 methods (from nostr-tools) for encryption and decryption. NIP-17 should be doable on top of that.
Discussion
Very cool, then why is nostr:nprofile1qqsrhuxx8l9ex335q7he0f09aej04zpazpl0ne2cgukyawd24mayt8gprfmhxue69uhkcmmrdd3x77pwve5kzar2v9nzucm0d5hszxnhwden5te0wpuhyctdd9jzuenfv96x5ctx9e3k7mf0qydhwumn8ghj7un9d3shjtnhv4ehgetjde38gcewvdhk6tc4rdlnm freaking out that nip44 doesn't work with frost?
honestly I didn't know of an ECDH solution until fairly recently. I stole it from Jesse Posner, full credit to him:
Wow, I didn't know this. Good to learn about this arcane knowledge here.
It is still kinda bad in the multisig bunker case because the coordinator can decrypt your messages, but better than nothing? I'll try to implement it.