Two years in Yogya and I still get most of my Indonesian practice from the woman who sells nasi goreng at the end of my lane, which is something, I suppose, if not quite what I expected when I arrived.
I've been doing something similar with ChatGPT for a few months now (same setup, basically, write in Indonesian, have it reply simply, corrections flagged). It does work for that specific thing. The part I can't work out is whether it's actually transferring to anything outside of itself, because the Indonesian around me here is very Javanese-inflected and sounds nothing like what the AI gives back, which is clean and formal in a way that real conversation in this city just... isn't.
The household I work for speaks Dutch and English, so I'm in roughly the same position as you, structurally, where the language is all around me but somehow not actually available. ChatGPT fills that gap in some sense. Whether it's the right gap, I dont know.
The "simple and repetitious" shopping thing, yes. that's exactly where I've been stuck for over a year. :/