Files app
Secure ShellFish lets the iOS Files app and Mac Finder connect to SSH and SFTP servers as if they were a cloud drive. You enable the Location for the app from the Files sidebar.
Each file and directory has a Manage screen reachable from the context menu. From there you can rename it, change Unix permissions for User, Group and Other (chmod), download or refresh, remove a local copy, or pin it with Keep Downloaded so it's available even when the network drops. Directories also expose an Exif Preview toggle that shows thumbnails for not-yet-downloaded photos by reading their metadata, paired with a thumbnail Shell Integration command for unusual formats.
Modern apps can open files in-place from the server, so an editor saves directly back to remote storage instead of round-tripping a download.
Pro users can stream videos from the Files app without download by picking Playback from the context menu.
You may need to enable ShellFish from the Files app sidebar the first time you use it. On a Mac, server files are also accessible from ~/Library/CloudStorage/ShellFish/.