I wanted a Markdown notes app that I could access over the internet, and stored files in a files-on-s3 structure that would makes sense if I accessed it directly and would be stupidly simple to backup/restore.
Ended up with an Amplify app that had basic login, file upload with image thumnbnails, indexing of frontmatter, some query macros to list pages matching specific criteria, autocomplete for frontmatter and macros, and ability to make specific pages public if I want to. Apart from login, it only uses direct S3 calls, so I'm effectively only paying for S3 storage costs.