Linux email app on Chrome OS?

I have a Chromebook running Chrome OS 80. I don’t use Gmail so I would like a stand alone email app.
I used flatpak to install Evolution, but was unable to get Evolution to save my password.
When I try to install Thunderbird I get the following error:

app/org.mozilla.Thunderbird/x86_64/stable needs a later flatpak version (0.10.3)

Does anyone know how I can force Evolution to save my password or how I can update to a newer version of Flatpak on Chrome OS?

Thank you

As I have no idea how Flatpak support works with Chrome OS, I don’t have specific suggestions. I assume it uses some Linux distribution to actually run flatpak?

Yeah, stuff is basically inside a well integrated debian buster VM. The out of the box version is very minimal, so to do things like access the GNOME system password storage you probably need more of a GNOME base in the bit of the system that ‘apt’ manages.

To get a newer version of flatpak you need to install it from debian backports. Instructions here:

That makes sense. This gets to the question how much effort do I want to put into this? :smile:
The more I use the Chromebook the more I like it, but in some ways things are just a easier on an actual Linux machine.