It would be great to be able view and edit plaintext or source files.

• This one feature would allow to work with dozens of file formats in different programming/scripting languages, config files etc.
• It would allow to create quick txt/md notes, where the full blown rich text editor is not required/desired.
• It would allow to use Markdown note vaults, like those used by Obsidian.
• It would allow to use tabular data in CSV format, which might cover some use cases for the (currently missing) spreadsheets feature.

In the future, it would be also nice to have some syntax highlighting for popular languages. But even without that, the ability to edit raw text would be a massive improvement.