iOS app text file without extension

I am using Calcurse a terminal calander app.
I sync it via Nextcloud among my devices.

I found that todolist and appointment files are text files without any extensions.
Those can be opened in iOS dropbox app but it is not possible in iOS Nextcloud app.

Is there any way to open text file without extension?

Or how can I let the nextcloud developers to know about it?

Thank you very much.

Files without extension are not that easy to handle.
For sure you can use some detection magic.

The other way arround:
Ask Calcurse to use suitable extensions.

Last chance:
File an issue at ios repo at Github. Not sure what is possible on iOS plattform.