Ok, so we know that canonically Amphibia and The Owl House take place in the same Universe (and Gravity Falls, but that's not relevant to this.)
And we know that, in TOH, there's the "In Between" place, and logically, one of the places it leads to is Amphibia.
The Collector made the permanent door to the BI, so theoretically, they could make Doors to other Places too.
Which means, if any of the Calamity Trio ever met anyone from the Hexsquad, and the topic of saving other worlds from ancient evils ever came up, they could get a permanent door to Amphibia.
And like, even if they couldn't make the door. Because they couldn't get ahold of The Collector on a whim, or because they're too afraid that the US gov will try to take over Amphibia again, Luz knows how to build a Door to the In Between
Which means Anne could at least talk to Sprig & the Plantars, through a mirror or something. Which is still 1,000x better than the heart breaking "have a good life, never see ya again" way that it actually ended.
Like, that is my least favorite trope in all of fantasy.
The idea of traveling to a different world. Then being imbued with God Powers
Then actually fucking dying and being reborn because the Will of Fate decided you needed to keep living.
Forging life and death bonds that transcend friendship and family.
Then it's just POOF ok back to academia and wage slavery and puttering out a mundane existence on this overheating rock.
Never experiencing the magic that you know is real ever again.
Never hearing from your found family ever again.
Like, I'm sorry, but I would simply perish. That's a nightmare I can't even imagine.
Everybody else take notes and fix it