@thelinuxcast I'm on Archlinux (Edit: I meant EndeavourOS) and it is currently in the extras-testing since days. If even the "stable" extras repository doesn't get it, then it means this is a complicated process with potential of problems. While I want it as fast as possible, but I also want it work perfectly after update.
@bruce I assume you need to give some permission to the Flatpak. You can do that with https://flathub.org/apps/com.github.tchx84.Flatseal . I don't know why this app is not installed at default for all distros that care about Flatpak.
@bruce I hope it will help, because I don't use Flatpak version of Thunderbird and it's just a shot in the dark. But even if not, Flatseal in itself is useful in general. For your actual problem, I am not sure if a) you want open PDF files from your drive or b) do you want open and read the attachment PDF file? Because if its a), then you probably just need to give permission to read the fileystem you want to access. But if its b), then I actually have no idea which setting is required.
@GentEL What is the context here? Is this an ad? Is this a photo shooting never released to public? Is this some random girl who looks like it could be Zelda? Is it AI generated art?