Well to be clear, that’s not exactly the same question as what’s posed in the OP
If you simply want to share files between two Linux servers, there are a lot of options, which may or may not be appropriate for usage with Discourse running on separate VPS. Here’s a couple
- NFS network filesystem, SMB share
- SSHFS ssh filesystem
- FUSE filesystem driver to mount your S3 as a local filesystem (or just use S3 directly)
In general I would just use S3 directly. You do not need to “run a second VPS just for storage” if you’re using S3