Alterantive Onlyoffice android app

Is there an alternative app since Onlyoffice android app is not FOSS and contains trackers?

Yes, OnlyOffice works in the Nextcloud android app (if the backend server is not blocking it).

Edit: You have to press the three dots on a .docx etc file and select “edit”. That will open the OnlyOffice editor within the Nextcloud app. Otherwise it will try to open another app

I’ve successfully used the Collabora foss mobile app with OnlyOffice. Tested on iOS successfully.