I just got back from korea. Esims are slow unfortunately but silent.link saved me in a pinch. I suggest going to one of the kiosks between exit 7 and 8 (maybe 6-7 i forget) to get a mobile Hotspot. Its a million times faster and u can connect multiple devices. Use mulvad VPN with it.
If you happen to go to the Misa area in Seoul, theres a bunch of restaurants by the river. Go near the lit up bridge and look up. Theres a hookah bar on the 2nd floor. Stop in for amazing custom cocktails and hookah. Tell him youre a bitcoiner and the previous guy recommended you. The international Bitcoin network is strong. Ive been working on orange pilling the owner. You'll see a Cleveland Bitcoin biz card on the bar by the door.