@User You mean any s3 storage or locked to supabase s3 storage buckets ?
I also have similar situation I am switching an existing application to supabase architecture.
My current project uses backblaze for storage, postgrest for api.
The app stores around 1 TB of images in backblaze which only costs me $5 per month.
I am looking for a way to use hosted version of supabase and use my own buckets to store objects.
backblaze is s3 compatible if that helps.