With online PDFs I use MS Edge and have enabled the Appcontainer renderer. For offline PDFs I use SumatraPDF portable to which I have blocked connections in the inbound/outbound firewall. I put Sumatra PDF portable in the LocalLow folder. Now the software has an Integrity Level low.
FYI. PDF-XChange Editor Portable 9.3.361.0 (PDF editor and viewer) Released for the PA Platform, courtesy of PortableApps.com
I had already included SumatraPDF portable with 13 rules in the anti-exploit list. If any forum member uses an app from the Microsoft Store (level Appcontainer) I would like to know his feedback.
FYI. PDF-XChange Editor Portable 9.4.362.0 (PDF editor and viewer) Released for the PA Platform, courtesy of PortableApps.com
FYI. PDF-XChange Editor Portable 9.4.363.0 (PDF editor and viewer) Released for the PA Platform, courtesy of PortableApps.com
On Android, I use Librera Pro (from F-Droid) on a tablet, and ReadEra, which works well on my cheap Android phone. The latter can be had from the Play Store or sideloaded from a trusted site. https://play.google.com/store/apps/details?id=org.readera On Windows, the latest Sumatra has become a superb epub/mobi reader, replacing the bulky Calibre for me.
You can always use the Secure PDF Reader by GrapheneOS: https://play.google.com/store/apps/details?id=app.grapheneos.pdfviewer.play https://github.com/GrapheneOS/PdfViewer/releases
FYI. PDF-XChange Editor Portable 9.4.364.0 (PDF editor and viewer) Released for the PA Platform, courtesy of PortableApps.com