As much as I like the idea behind Pine64, make sure you understand what you're doing - their devices usually need some time before they're useful, they might underperform, etc.
On the other hand, they're usually priced well for what they offer, and I think the ARM model of new PineTab might look better than their usual new offerings. Make sure to find out, how polished it is before you buy.

It's the moderation staff's responsibility. Sorry for nitpicking, I understand in this case it's likely the same people.

I just get triggered when I hear that an open source software developer should have any responsibilities at all (maybe apart from some extreme examples), and I wouldn't like this idea to stick in anyone's head.

From what I understand, the RISC-V ecosystem is not polished enough yet, so the state of PineTab-V roughly represents the state of the entire platform for desktop Linux.

My personal workaround is a smartphone book case with a spot for the debit card.

The entire idea of Ubuntu Touch device support, was to be based on Halium. It's a bit different than regular mobile Linux (outside of Droidian, of course), where mainline is a requirement.

Looks like they have valid reasons for doing this - also, remember: they still allow selfhosting. It's less about what they want to do, and more about 'people are shit, as usual, and this is why we can't have nice things'.

• KeepassXC should just work, if the browser's key was added to your KDBX database successfully. Other than that, I am surprised.
• Yup, the motherboard clock thingy is a consequence of Windows storing local time, vs Linux storing UTC. It's a minor thing to fix in any of these systems, though.
• Shortcuts thingy - never had a problem, although I did have a problem with KDE's keyboard shortcuts to run a program, which may be related workflow and maybe both were/are broken.
• KDE Connect is surprising, as at least for me it worked flawlessly
• The reboot thingy must be related to Linux Mint. I saw similar thing in EndeavourOS. One nice thing that some distributions implemented, is the ability to apply updates when you poweroff - from my point of view it's a less annoying solution than what you describe.
• I can't comment on the 'cherry on top' one without more details.
  I had a somewhat similar issue on my work laptop a short while ago, when I installed a program, which included a bugged XML settings file, then ran system update. When the updater tried to rebuild some caches (related to ie. icons, MIME etc.), some programs which use these caches simply stopped working. Reinstalling all packages with apt was the only thing that helped, to this day I do not even know all of the parts of my system that were broken.
  But this was one of these issues that happen once per 5 years, and leave you scratching your head and asking "what the hell is going on here?". The difference from Windows is that in Linux, you can have a high understanding of system's internal modular components (at the cost of time needed to learn it), and regular system issues can be identified after a few minutes of Googling.

I'm as skeptical as you are, but at least they automatically preinstall a few useful gaming apps by default, ie. LatencyFlex.

Oh, and as for the touch UIs, not much luck if GNOME doesn't work well enough. KDE can be made to run well with touch input, but for me it needed some work to configure it. But I liked it afterwards.

There are Mobile Linux UIs (which might run better on tight resources) but I am afraid they might not be good for multitasking on a tablet screen.

Mobile Linux distributions for smartphones might offer some hints on how to tackle your problems - these apps are created in a convergent way, which makes them work well on laptops, tablets and PCs alike. Look for an alternate file manager, for example, to replace Nautilus. Check out https://linuxphoneapps.org/apps/

What do you think about using a keyboard-based workflow: hit Super button (or click on Activities) to make the fullscreen menu pop-up, then write the first few letters of the app name, and finally hit Enter? Search-based workflow is my favourite way to navigate app menu, on GNOME and KDE alike.

Maybe it's obvious, but how about Kodi?
It has support for CEC (for utilizing your TV's remote through HDMI), of course there are other input options as well.
There's plenty of plugins to support online video services. Needs some work to configure them, and sometimes it requires maintenance when a plugin stops working, but I was in general happy with the way it worked while I used it for a few years.