You are not wrong. However x86 is dead to me for having a BIOS level backdoor built in that you can't get rid of (probably; yes I know about ME Cleaner). Not to mention Intel sat on their laurels for years. ARM are far from perfect, but maybe some competition gets things progressing again.
You asked about mini-PCs, which I don't have, however just for comparison I can say I have ODROID-XU4 + cubietruck here running and only drawing about 2W total between both of them.
I wouldn't necessarily recommend those (especially the cubietruck) these days, but there are lots of Single Board Computers (SBC) out there besides RPi.[0]
Any old desktop from a garage sale (if you can find one). People are practically giving them away these days, everyone wants tablets/phones now. We scored a quite decent one, complete with monitor, mouse, keyboard, etc. for like $25 (IIRC)!
In fairness, that was a few years ago, but I am sure there are deals to be had if you look around.
I would not recommend ARM/SBC for "first GNU/Linux computer" necessarily, you will likely have an easier time on x86, as much as I hate to say it.
It's not just them, the majority of SBC manufacturers are on these bizarre old Linux forks that have been patched all to hell and will never see mainline. Kind of same situation with most smartphones, too (as they are all the same SoCs).
There are some very noble projects (like PostmarketOS for phones, and Armbian for SBC) who try to be "mainline first" to keep these fascinating little devices going longer (and more reliably). They do an amazing job considering what they have to work with, but these are not big companies with a lot of resources behind them, so if you care about this sort of thing (not you specifically, that's for anyone reading) then consider perhaps lending a hand (or a few bucks)!
But x86 boards have vastly fewer kernel & driver support problems.
It's not even close, not even in the same order of magnitude.
The problem is not "sbc", the problem is "arm sbc"
Running on a random "unsupported" x86 board is no more of a problem than an unsupported laptop. There are sometimes no drivers for some peripheral but it's nothing like arm where you can't even boot without a dtd and most of the hardware has some freak custom interface instead of just pcie and usb and well known chips.
Every single arm board is like it's own whole different platform. A Bananna Pi Foo A and a Bannana Pi Foo A+ both with nominally the same cpu and specs might as well be a trs-80 and an appollo guidance computer when it comes to bringing them up.
IMO the logic is reversed. Wintel phenomenon created enormous incentives for everyone to follow IBM PC "spec". That was odd, and it's ARM SBC situation that is more normal.
