Cannot access plain text files with "unusual" extensions

I would like to edit .tex files in my nextcloud. But neither I can open it with the internal editor nor can I get access via the file viewer of ios. The only way is to download the .tex-file. But in this way, it won’t be synchronized anymore. It is possible to allow open/change/… other extension than .txt, .pdf, …?

[at least one can do it for the web interface…]


The internal editor is limited to a few file extensions.
The latest app version supports “Documents”. So you can use any text editor which uses “Documents” as well to edit files and they are synced e.g. Pretext for Markdown.