I came across a related discussion some time ago and actually shared it in another post here in the community.
It’s based on an experience shared in the Nothing Phone Indonesia Facebook group, where a user mentioned using a Realme C1 BLP729 5000 mAh battery as an alternative replacement for the Phone (1), mainly because official spare parts were difficult to find in my region.
Just to be clear — I’m not recommending this approach, I only shared it as an alternative reference for users who might be facing the same spare part availability issue.
I’ll drop the post link here in case it helps.
https://nothing.community/d/51834