With the recent firmware update, the BlockStream Jade can work like the SeedSigner.
I leave the Jade as uninitialized, so it does not store any seeds. To use it, just turn on Jade, scan the qr, and it will temporarily load in the seed, and then it will work with Blue Wallet or Nunchuk on the phone perfectly.
It is cheaper, $49 vs $80 (prebuild SeedSigner). And if you want to build a SeedSigner on your own, the Raspberry Pi Zero is unreasonably pricy nowadays.
Another plus for Jade is the built-in battery, so it can work on the go. It also supports Bluetooth and usb, but I prefer to keep it fully air-gapped. I don’t use the official Green wallet app anyway.