Some Korean apps are only available on the Korean App Store or Google Play Store?

This was a frustrating issue I dealt with when I first arrived. Here is what works.

For Android. The Korean Google Play Store is automatically used if you set your Google account country to Korea. To switch country, go to Google Play settings, change country to Korea (requires a Korean payment method on file, but you can add a Korean credit card or use Google Play gift cards). Once switched, you can download Korean-exclusive apps like KakaoMap, Daum, Naver, and Korean banking apps.

The limitation is you can only switch countries once per year on a Google account. Workaround: create a second Google account just for Korean apps, and switch only that one to Korea.

Alternative for Android: download APKs directly from sources like APKPure or APKMirror, or from each Korean company's website. KakaoTalk, Naver, and Coupang all offer direct APK downloads. Less convenient but no country switching.

For iPhone. You need to create a separate Korean Apple ID. Go to Apple ID settings, sign out, then create new Apple ID with Korean country region. You will need a Korean payment method (Korean credit card, KakaoPay, or Apple Gift Card purchased in Korea) and a Korean address. You can keep your existing Apple ID for purchased apps from your home country, but downloading new Korean-only apps requires logging into the Korean Apple ID in the App Store specifically.

Warning. Apps purchased on one Apple ID are tied to that ID. Switching breaks subscriptions. The workaround is to use two devices or accept buying some apps twice.

For banking apps specifically. Korean bank apps often require a Korean phone number, identity verification, and sometimes a special USB authentication. They may not work on phones with non-Korean software keyboards. Some banks have a 글로벌 (global) version designed for foreigners that works on international Apple/Google accounts.

For most foreigners, Android with a secondary Korean Google account is the simplest setup.