If the red twilight (astronomical) never fully disappears. Do I pray Isha 1h after magrib like sheikh Muhammad Hisham said. Or is it more authentic to follow the country closest to me that has Isha time? Is this (following closest country to me in Isha) even a saying of the people of ilm?

Ustadh AbdulAziz al-Haqqan

If your condition is the same condition as the one that Sheikh Muhammad Hisham (may Allah subhanahu wa ta'ala preserve him) answered, then yes, take his answer.