As far as I have heard BitVault already supports the Hardware Wallet Blockstream Jade and Foundation Passport via QR-Codes. So it should be not that hard to implement another AirGapped Hardware Wallet the Specter DIY Hardware Wallet.
Here is the GitHub to the Specter DIY Hardware Wallet:
https://github.com/cryptoadvance/specter-diy/
As you are implementing the Specter Hardware Wallet it should be very very easy to have SeedSigner and Krux also implemented.