nfsm

I would stick with SMB and SSH(SFTP). SMB for content sharing and accessible on any device like PCs or phones. SSH, which includes SFTP, for accessing everything else on the server.

+1 for bazzite. And OP had already worked with fedora

Fedora atomic (I'm using bazzite for gaming only) have Flatpaks enabled by default and are recommended, so it integrates well with the OS.
And seeing where the Linux community is going right now, Flatpak has been widely adopted by most distros which are not Debian based. There are ways to go regarding the packaging for the developers, but there are plenty of apps already on flathub. I'm using it on arch and bazzite and have no problems so far.
I can't comment on the apps the OP requires

Security starts first with you. Most of the attacks are done though social engineering. Email phishing, dodgy webpage logins. Normal password security behaviour should fine for you to use the pc. More importantly, what is the distro you're using? Maybe consider using Flatpaks for the apps, they tend to offer more restrictions on access to the system. (Installing the torrent app as a Flatpak and only give it permissions to a specific folder) One of things I tend to do is install chromium just to login on my Google apps, Gmail, YT. But I'm more of a non data sharing freak.

I work on IT support and all of our clients use enterprise. It's not just the Ads.
Microsoft has slowly been dumbing down it's apps and the OS. Removing features that where good for office users.
Access to settings is a joke. It's a bad OS. I fell like they've gone backwards, again.
My pet peeve right now is why can't the taskbar be placed on the sides? It had that functionality before.

Hardware issues have been fading more and more. Just recently saw a small survey in a Linux channel with about 1000 responses. And about 50% retired no issues with hardware plus a lot more that only had 1 issue (there are still some vendors who don't offer compatibility like AMD or Intel). So most people don't actually need to download drivers, it's all in the kernel.

I haven't noticed any issues. But only Plasma would be a DE. Qtile and hyprland are WM, not sure if that makes the difference.
Initially I had doubts if it would work, but so far so good.

Nice work. Why move from plasma to hyprland? Install both and login on the environment you want at any time. I have qtile, plasma and hyprland

Have a look at this.
https://pine64eu.com/product/pinetime-smartwatch-sealed/

You can see the specs and get the idea of what you might need

I use it on my home server, TUI only, when I want to organise my files

Enjoying so far. Thanks