How to install Debian .deb package using GTK?

[sedubois]

One thing I'm still missing in Omarchy is an application which I find neither using Install > Package nor using Install > AUR menus (there's another package with the same name which is unrelated). I can download it directly from the app's website, but only in .deb format. I see online that I can try to install it using:

yay -S debtab
sudo debtap -u
debtap falco-app_4.3.1_amd64.deb
sudo pacman -U falco-app-4.3.1-1-x86_64.pkg.tar.zst

I ran this last command using all the defaults (e.g did nothing special when asked if I want to edit .PKGINFO and .INSTALL files).

But it gives an error cannot resolve "gtk", a dependency of "falco-app":

sudo pacman -U falco-app-4.3.1-1-x86_64.pkg.tar.zst
loading packages...
resolving dependencies...
warning: cannot resolve "gtk", a dependency of "falco-app"
:: The following package cannot be upgraded due to unresolvable dependencies:
      falco-app

:: Do you want to skip the above package for this upgrade? [y/N] y
looking for conflicting packages...
 there is nothing to do

Would anyone have any suggestion on how to install such a package? To make Omarchy my daily driver I think I need this app to function. It is only available as a native app, not a web app.