I use the Android version just now offline with wifi and mobile network off and I was able to create a wallet with it. I went to where seed phrase is I saw the seed phrase. It worked offline. I mean Blockstream Green.
Bluewallet is also working offline when I tested it last. I checked it now and it worked also. The only problem about the wallet is that it is heavy to load at first but it will work.
I tried it two times and both times it game me same error. Ill try to recreate this situation one more time and send screenshot. I don't know if it is possible that cell phone model is cause of that error?
But as an alternative, you can check Electrum (for android) or Unstoppable wallet.
It's may worth mentioning that the seed phrase generated by electrum isn't BIP39. Electrum uses its own algorithm for generating seed phrase.
If you want to have a BIP39 seed phrase, you can generate an electrum seed phrase and then change the last word until the seed phrase passes BIP39 checksum.
I recreated wallet with seed that I got from Blue wallet in Electrum that ran on Tails OS. There was message in Electrum that it uses different word list, because BIP 39 does not satisfy their security standards. If I remember correctly BIP 39 don't include version of software or BIP standard (I know something about versioning was the reason). I insisted on BIP 39 because more wallets support it and I guess this is most widespread wallet standard now.
Edit. Added this reply that was posted before I clicked send button.
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What could be good alternative to Blockstream app to generate BIP 39/ BIP 44 compatible wallet ?
If I were faced with the similar task, I would probably use flipping coin to generate entropy and subsequent SEED phrase for my wallet.
Pros:
- Truly airgapped and offline method
- which doesn't require trust in any RNG
- and besides is free of backdoors
If you are interested find step-by-step guide
here.
I first considered to generate seed words by hand, but calculating checksum (12th word) seemed too complicated. I don't have any software to generate hash and I know very little about cryptography so I simplified seed generating processes by using wallet software.