Only two features missing from Sparrow that I've been able to find are ability to set feerate on a sweep private key transaction and that a signed psbt from seed signer does not successfully import when using the "open transaction from QR" feature. No one is perfect but it's getting damn close @craigraw 

 1. Check out the most recent Sparrow release. 2. SeedSigner is providing very minimal, arguably incomplete PSBTs so without another PSBT to combine with (as would be the case with that function) Sparrow doesn’t have enough information to load them on their own.