Like "radio" or "fantasy" or "game..." They're basically the same in Japanese (radjio, fantaji, gaamu) so if I just said them in English pronunciation, would someone with no experience in English still be able to tell what I'm saying?
Idk for shure but pretty likely also most people around the world nowadays do get English education at least a little so its probably hard to find one that doesn't know English at all, at least among the younger people.
Adding my experience in Japan real quick, this is a bit more likely to be the case in huge cities like Tokyo, but the majority of Japanese folks I interacted with in Tokyo and Kyoto had an understanding of English the same way you would if you took Spanish all through highschool (or whatever your local equivalent to this analogy is). They could sort of understand very basic phrases, but I wouldn't expect a conversational grasp.
I think it depends on the person you're speaking to and how good they are at understanding accents. Because that's essentially what you are describing. When someone says a word in English using pronunciation guidelines from their native language, you hear that as an accent. The same would be true here, even though the words are loan words. They are used to hearing it through their own pronunciation guidelines, so it might take them a while to decipher it.
My experience is no. Now sure why, but in your example, the a sounds are difference. rah-djio vs ray-dio.