I’ll second Debian. I run it on backports and it’s reasonably stable, but if you want it rock-solid, don’t do that.

You might want to keep your browser more up to date than the rest of your OS. That’s up to you as the user. Mozilla has a deb you can add to Apt manually, should you choose.

Extended Security Updates.

I agree with you on throwing out perfectly good hardware. Either you hang on it until it’s useless, or you throw it on eBay and let someone else have it.

That’s fair. My UniFi gear has added that in recent updates, though that’s an investment. If your system works for you, that great; stick with it!

But, I would try to find an alternative to Windows 10. Paying for ESU’s would be better spent getting something else. What that might be, I’m not sure.

Is there a reason you’re making your own access point instead of buying an off-the-shelf one? I know you said you don’t want to spend more, but a proper AP would let you simplify your server and remove the Windows VM entirely while still providing greater than Gigabit speeds (depending on the speed of your switch ports).

Apple tried it a decade ago. It was called the Fusion Drive. It performed about as well as you’d expect. macOS saw the combined storage, but the hardware and OS managed the pair as a single unit.

If there’s a good tiered storage daemon on your OS of choice, go for it!

Are you old enough to remember Winmodems and NDISWrapper? There used to be some hardware that was so cheap that the Windows driver needed to do some of the basic work. They were never compatible with anything but Windows (and maybe 98 or XP at that). I’m sure there were some printers like that.

Combined with poor driver support early on, and a lack of standards (at least on the consumer end), and the need to have a separate PPD file for every make and model of printer, and printing used to be a mess. (It almost got bad again when Microsoft tried pushing their XPS format as a replacement for PostScript, PCL, PDF, and EPS, but that didn’t catch on.)

Apple buying CUPS (and hiring its lead developer) was great for the community. They got it working all but perfectly. I’ve never had a problem printing on Linux; HP, Brother, or otherwise.

FYI: the developer quit Apple and forked his project into OpenCUPS, but I haven’t tried that.