Hello @isaric ,
Welcome to the forum and thanks for the question. 
I’m translating your French message into English using DeepL:
Hello,
I want to retrieve cells from a Calc (LibreOffice) sources.ods file.
When I query URL of the .source.ods file installed on Nextcloud, it opens Collabora.
Can I access the values of certain cells in the file_sources.ods
file and integrate them into another file, as can be done with an HTML page:
https://help.libreoffice.org/latest/fr/text/scalc/guide/cellreferences_url.html
Thanks in advance
No. You currently can’t link to specific cells or to pull data from specific parts of external files.
For more technical info, see these 2 previous topics: