Yeah, may be it's really somewhere alien. The robot enemies we saw so far do look like aliens.
My first guess is Starfall Island could be an alien spacecraft that landed on Sonic's planet and became an island. But that doesn't explain the foliage on it that looks like it would of been there for centuries.
My other guess is Sonic probably goes planet hopping again. This isn't exactly a new thing since Sonic Colours, especially SC:Ultimate we had lately, it's just I'd rather we don't blur the lines between what is Sonic's world and what is Earth again.
May be they want to show that he's strong, not just fast, which is kinda strange.
As if they mistakenly him with Knuckles.
Knuckles would of been an interesting choice.
Netflix officially announced UNCLE FROM ANOTHER WORLD Coming to Japan in July!
Rest of World Coming Soon!
Source : https://twitter.com/NetflixAnime/status/1534680674543738880
Still looking forward to it, even if I'm probably hyping myself up for an anime I may find mediocre just for the Sonic.