What app should I use on iOS?

[heed822]

What app should I use on iOS?

https://apps.apple.com/app/polarios/id1662366309

This app is currently unavailable in your country. (Korea)

[lnicola]

Looks like Polarios is third-party, and not really active lately: https://gitlab.com/elise/Polarios.

[heed822]

https://gitlab.com/elise/Polarios.
The app here cannot be installed due to regional restrictions.
Is there any other alternative?

[lnicola]

There are no alternatives listed in the README, but why not ask about the regional restrictions on https://gitlab.com/elise/Polarios/-/issues/? Maybe the developer is still around and can tweak them.