Is this dislike of Flatpak unique to the Qtile flavor or an endeavouros-wide ideology/tenet?
Installing Flatpak using pacman or yay works, but is not as fine tuned as some other distros. For example when you run flatpak install ..., Pop OS will ask you whether you want to install the app for the current user or the whole system before proceeding with installation but on endeavour flatpak by default assumes you want to install packages system wide (unless you explicitly pass the --user flag).
Anyway. It is good to know that out of the box flatpak is not planned for this flavor. A pity IMHO, but understandable otherwise.
And regarding OnePassword (or more officially 1Password), you can google it, and you can install it directly:
Also one common issue that Arch users have is that installing non official packages sometimes breaks the system after cycles of new rolling releases, etc. Flatpak apps are less likely to break due to that.
Flatpak is not planned for any flavor or to be setup in any DE/WM in Endeavour. EOS is a building block for your own computer. It’s intended to be Arch, with yay packaged and a welcome app with a few basic tools. Most things are not intended to be there OOTB - > including flatpak. It’s not a pity, it’s a privilage actually! You only have to add things you want instead of remove things you don’t!
I actually have no real problem with flatpak at all. Outside of Arch, it’s my preffered method of applications.