Hi there, I'm still in the process of finding a therapist but strongly suspect I have ADHD. Task stacking is really stressful for me as well. In addition to that, there are a lot of places and things in our flat that represent unfinished tasks that I have to ignore to get started with anything at all.
Then maybe the downloaded packages are actually corrupted. You could check if they have plausible file sizes. IIRC pacman will ask you if you want to delete the non-matching files but I'm not entirely sure. They should end up in /var/cache/pacman/pkg.
g is the acceleration applied by Earth's gravitational force (for masses much smaller than Earth's, that are pretty close, i.e. essentially everything you typically interact with) and is approximately 9.81 m/s^2
I did use franz at some point but eventually switched to ferdium, which doesn't require an account. That being said I haven't used either for a while now.
I know it sounds dumb, but lying still and thinking the same word over and over seems to help me if nothing else does the trick. If you notice yourself thinking something different just get back to it.
For your first point you'd probably want to investigate why your system doesn't suspend or what exactly is going on. You could check logind.conf, specifically the HandleLidSwitch* keys. Otherwise, your lid switch should have a corresponding /dev/input/ event that you could maybe listen to or something.
I can't offer much input on your second point. I think unplugging the audio jack should probably trigger a udev event that you could write a rule for. No idea about wireplumber though.
I'm pretty sure Solus is a Linux based OS, at least according to Wikipedia:
Solus (previously known as Evolve OS) is an independently developed operating system for the x86-64 architecture based on the Linux kernel and a choice of Budgie, GNOME, MATE or KDE Plasma as the desktop environment.
kmail is in the arch repository (in extra), the package is called kmail.