There no way even possible via the GUI to config power management for things like low/critical battery conditions /actions on Linux.

I don't think you should bash Linux for choosing an immature desktop environment.
KDE has this and I don't think it's a new feature. System settings, power management, advanced power settings to set low and critical levels and what to do at critical, and "energy saving" menu to configure everything else. The interface is better than any windows implementation of this that I have seen.

Yes I've also been frustrated by the inferiority of the default mint DEs, but saying that Linux can't do those is not true.

Every time I've installed Linux as my main OS (many, many times since I was younger), it gets to an eventual point where every single thing I want to do requires googling around to figure out problems

For me windows would be the same if I ever reinstalled it

can't wait to search for some drivers so I can get the cursor acceleration disabled. Or enabled. Or configured?

KDE, configurable in system settings gui. For ages.

Linux doesn't even use a common shell (which is a good thing in it's own way), and that's a massive barrier for users.

There's no single shell that's true, but why do you think bash is not common? All distros I have used so far (debian, ubuntu, mint, suse, arch (no I don't use it by the way)) has used bash.
After finishing the sentence, I realized you probably mean the desktop environment. Yeah there are pros and cons of all of them, I think KDE is the most suitable for most uses but for old machines maybe it's not what I would choose.

settling on a single GUI (which is arguably half of why Windows became a standard

Windows does not have a single gui. They change it roughly every 2 major OS versions, and recently they are not just changing it but turning it into a steaming hot pile of garbage, first with the settings app in 10, and now full-on in 11.