airgap-coin-lib VS bip39

The audit reports have been released over 2 years ago (shortly after the audit report was done) and are available on github: https://github.com/airgap-it/airgap-coin-lib/tree/master/docs/audits

That being said, I can tell you a little bit about our experience. We developed our wallet to be blockchain agnostic from the start. All the coin specific logic is located in a shared library that is used in both the Wallet and Vault application (https://github.com/airgap-it/airgap-coin-lib/tree/master/packages/core/src/protocols). We have an interface for methods to prepare, sign and broadcast transactions, as well as generate addresses and fetching balances. To add a new coin, all you have to do is add a new class to the shared lib, implement all the logic and then add the new chain to the "supported protocols" in the apps. Everything else is handled automatically (besides coin specific features like staking, etc.)

AirGap was audited a bit more than a year ago by "Compass Security". The review is available on github: https://github.com/airgap-it/airgap-coin-lib/blob/master/docs/audits/report_85096_mobile_app_security_v1.0.pdf

Download the offline version of the BIP39 tool via https://github.com/iancoleman/bip39/releases/latest. Right click on bip39-standalone.html and save the file.

You could make this with a Raspberry Pi Zero and the stand-alone version of the Coleman Web page+javascript https://github.com/iancoleman/bip39/releases/latest/

Since what I just said may be confusing... here it is in practice with a link so you can try it for yourself using Ian Coleman's Mnemonic Code Converter:

With Christmas coming around and the bull market upon us, I thought it would be a good time to remind everyone one about the art of mnemonic memorization. The idea is you take a BIP39 seed, then make a poem, story, limerick, or song using the words to help you remember. If you gift bitcoin, you can include the writing with the seed-card you provide to help the recipient remember as well. If you want to play along, go to Ian's BIP39 page and generate a valid seed mnemonic then see if you can't create a blurb of text that includes all the words.

You can try Ian Coleman's tool at : https://iancoleman.io/bip39/

13) Go to https://iancoleman.io/bip39/. There you need to change "Coin" value of the dropdown to "ETH – Ethereum". After that you can paste Secret phrase associated with Key 1 to “BIP39 Mnemonic” section