They talk about ‘Metal Galaxy’, ‘PA PA YA!!’, Glastonbury 2019, their first show, and more. Check it out:
Joakim Brodén, lead singer of Sabaton, and featured artist on "Oh! MAJINAI" from METAL GALAXY, talks a bit about the process of recording for it.
It appears to have been a very off-hand experience. He explained the process in a talk with Herman Li of Dragonforce.