I'm writing this from an M2 Air running NixOS via the Asahi bootloader installer and it's an absolute delight. There are a few missing packages for the architecture, but surprisingly few. Everything works fine, except the fingerprint reader. (Having said all that, I like macos just fine.)
pukeko
Love this. It's related to one of the reasons I have recommended NixOS more often than I would have expected (not, however, as often as Fedora, Mint, etc.): if you're heading into a new way of using a computer anyway, why not go with something that forces you to abandon assumptions and learn something truly new? With the side benefit of effortless rollbacks if something you fiddle with goes horribly wrong. :)
But, no, at risk of violating rule #1 in your post, just pick a distro, don't worry too much about which, pick a desktop environment, don't worry about which, use the machine, and if you have a negative experience only then remember that you can try another desktop environment, distro, etc. Eventually you'll get to a distrohopping phase, but until then it's just software and a computer is just a tool.
Darktable has an astonishingly odd UI. It's a very, very powerful piece of software, but the workflow and assumptions are unlike any other software tool I've used. That's not necessarily a bad thing, but if you're looking to make a few luminosity adjustments as in Lightroom, it's going to feel alien. RawTherapee isn't, I suppose, as powerful at the top end, but it's much more accessible initially.
You might also want to look at Rapid Photo Downloader for easy and consistent photo importing to the filesystem.
My kid (not even a teenager) uses Linux daily. And not in a coy "he's using a chromebook" way. He's using full-blown NixOS on a laptop I set up for him. Could he have set it up? No, but he's a child. Has day to day use presented him with any difficulties whatsoever? Nope. He figured out gnome purely by instinct in a day. He goes between macos and windows and linux effortlessly, because he's a reasonably intelligent human being.
But, yes, half the time the "linux is hard" crowd seem to be basing their evaluation on things you would rarely do on a mac or windows machine. These days, install Mint, Fedora, or, hell, even Nixos or Endeavor, choose the defaults, and you will very likely have a perfectly usable, intuitive system.
The real thing. https://github.com/tpwrules/nixos-apple-silicon/
I wouldn't say it's something anyone can do (no graphical installer and updating is a bit manual) and it's all dependent on the Asahi folks, bless them, but it took me about 20 minutes, other than whipping up a machine-specific configuration.nix and home.nix (about 20 more minutes on either side of the installation). All of the instructions were clear, though I will warn that some of them are not well presented in that there are instructions that should be bullet points that are stuffed into paragraphs. Nothing remotely exotic though--that's all in the Asahi stuff that is wonderfully hidden from the view.
A last generation ThinkPad is still going to be a beast you can get 6-7 years out of. I have a gen2 X1 that was still a beast until the offspring spilled a Coke on it.
Get a refurb T14 for (relatively) nothing before going hardcore.
Looks at M2 macbook running NixOS
Ok maybe I do need help.
I had a thinkpad that got much of the way there. I never tried ZFS encryption, but I'm sure someone in the nixos world has figured that out.