Cool concept but...
I have the Solo card and the Solo steel can’t wait to try both but they both seem very solid and well-made. I had no issues setting up the card eventho the NFC didn't seem to work on my iPhone.

Archived App
This is an archived listing of the app previously available on the App Store.This application helps you recover your cryptocurrency private keys using physical "Solo bars" or "Solo cards" that contain secret codes. It computes and displays your private key on your phone after you input the codes.
1.3.0
March 22, 2021
Recomputation of private keys for Tezos, Litecoin, Bitcoin, BitcoinCash and Ethereum SOLO products
COINPLUS recovers private keys by using two secret codes engraved on physical "Solo bars" or "Solo cards." These codes are used to compute your Bitcoin or Ether private key, which is then displayed on your phone.
COINPLUS is available for iPhone, iPad, and iPod devices, allowing users to manage their cryptocurrency keys on Apple mobile devices.
The "Solo bars" and "Solo cards" used with COINPLUS feature tamper-evident holograms. The application itself computes and displays the private key on your phone, but the developer is not responsible for the device used to operate the application.
COINPLUS has an age rating of 4+, making it suitable for a wide range of users interested in cryptocurrency management.
The latest version of COINPLUS was released on March 22, 2021, indicating it has been updated relatively recently.
COINPLUS has a rating of 4.0 stars based on 1 rating, suggesting positive user reception for its functionality.
The provided data does not specify if COINPLUS contains advertisements. However, it is a free application and does not have in-app purchases.
The application requires inputting secret codes from physical devices to compute private keys. While the computation itself might not require an internet connection, the process implies the need for the physical "Solo bars" or "Solo cards" to be present.