Open File with known application doesn't work

Hi there,

I did a standard installion Ubuntu Unity 24.04 from here. The installation comes with Firefox, Thunderbird, OpenOffice and a PDF-Viewer and I think they are installed as snaps. I asked for help in Ubuntu IRCs and Foren, but nobody could help. All they said is that this is a snap problem not an Ubuntu and not a Unity problem.

I would like to open Files inside one application with another application, but the open dialogue only lists a ZIP-Tool. How can I change that?

Szenario 1: I downloaded a ODT-File with Firefox and want to open it directly in Writer, but all I can do is save the file. Open Writer and open the ODT-File inside Writer. Same for the other Office Filetypes and PDFs.

Szenario 2: I want to do exactly the same as Szenario 1 but with a Thunderbird attachment.