
I’ve found a possible solution on superuser.com. It’s basically copying the credentials from Linux to Windows.

I’ve found a possible solution on superuser.com. It’s basically copying the credentials from Linux to Windows.
Starting in July, Debian will not provide further security updates for Debian 10. A subset of buster packages will be supported by external parties. Detailed information can be found at Extended LTS.
The project is managed by Freexian. Their customers decide the scope of supported packages but updates and security fixes will be available for all Debian users without cost.
So basically, as veryoldoldstable it will be kept alive for another five years.

To make that more clear, you can use KDE software without Plasma desktop in example.
Like for example KDE for Windows, where the system is not even Linux.

along with Debian
Debian uses separate repos, which are incompatible to Ubuntu.
Snap and Flatpak are both available as packages. I don’t know about the availability of snap or Flatpak packages in the graphical ‘appstores’ in Ubuntu or Mint, but in Plasma Discover both are available by plugins.

That’s always a good idea

Yes, that works. Just install some KDE plasma desktop metapackage of your choice and, if you like, you can remove cinnamon and related GTK packages afterwards by removing libgtk.

I mean the deb-repositories which are of concern for apt. Mint is basically Ubuntu plus an additional repository and thus binary compatible.

Or if OP wants to stay in the Debian/Ubuntu based branch: KDE Neon, Debian with KDE (+ LMDE repo), or Kubuntu 22.04 + Mint repos.

AfaIk, Ubuntu uses some snap packages, e.g. Firefox, not the whole DE.

Why should the experience be essentially different from Kubuntu 22.04, as it uses essentially the exactly same repos?

That’s odd. I hate closed eco systems.

If proton supports CalDAV (I’m not sure), it should work e.g. with DAVx5 which integrates well with Android calendar.

More elegant than running an entire Linux system in a vm.

Maybe you were hoping that there is an easy and elegant solution like Appimage, Flatpak or Snap.

Surely not the most elegant solution, but you can download old Gnome live ISOs of e.g. Debian and run in a VM.

That makes sense, as most users automatically use the most recent version and don’t need to downgrade to prior ones.

It should, however, be possible to install old versions using flatpak.
I doubt it is even possible to be done in learning e.g. Python.
Nice