Google has such rampant influence that it’s difficult to block them completely with uBlock Origin or DNS solutions. However their corrupt surveillance can be reduced using some of the tactics and software in this article: https://simplifiedprivacy.com/how-to-reduce-googles-control-over-you/
Can you edit on the fly or a download, edit, re-upload situation?
Do you mean weather Filen desktop clients can sync folders between your computer and the cloud? The answer is yes you can. If it detects you edited a file in a watched folder, it will upload the file to the cloud.