Saga-gis is necessary to work with Qgis proficiently ; many options it provides are simply not built-in.
I’m pretty much dead in the water. I only began to work with GIS software, and the tutorials I need to follow depend on this package.
Also, consider to install python-wxpython-dev as the current python-wxpython doesn’t work with wxgtk3-dev.
If you’re bold enough, also consider to update your grass to grass 8 by editing the PKGBUILD according to the AUR page. I hope the current grass maintainer could update it, as grass 7 doesn’t work with python 3.10.