I would prefer it to be open source, but at this point that’s not a necessity. I need an app that can open word documents, powerpoint presentations and excel spreadsheets (maybe PDFs as well but I could always get a separate app). So far I’ve tried Openoffice & Libreoffice Document reader from F-droid which worked fine for documents but simply would not load pptx or xlsx files. I’ve now installed WPS Office from the Play Store but all the conversion options are clogging up the share with… options every time I want to send a picture. I would appreciate any recommendations at this point.
Just turn off internet access and disable permissions such as location and microphone if they’re there, you should get decent privacy. I use WPS and it works quite well.