It's just as easy to make a mistake with git today as it was however many years ago; git hasn't fundamentally changed in ways that make it easier. Git still more/less requires you to have a good understanding of what's going on in order to be comfortable using it.
But, since use of git is now widespread, it's less of an issue. And the git CLI has seen some UX improvements.
Nix is very weird. I'm sure there are some ways its UX could be nicer; but to some extent, doing things in a strict/pure way is always going to have friction if the tools/environments don't easily support that.
Pro tip from an actual pro :
git became significantly easier for me once I decided
1. to just use a good comfortable gui (at least one tui also look good) for anything beyond commit and push. (maybe not everything can be done from your gui of choice but at least you get a good overview of the situation before you dive in with the cli.)
2. and to just stick to the basics. (And when you need to help someone else who didn't, take it carefully even if that means you don't look like a wizard.)
In fact even working on the command line feels easier once I had worked in a good gui for a while.
Don't believe experts who claim that you need to study vim and stick to the git cli to "get it".
But of course: if cli is your thing, use it, just stop writing blog posts that claiming it is the only true way.
I do agree with you that some workflows are just easier with a GUI, since I used to use TortoiseSVN and it was much nicer for diffing two commits than the CLI is. But I haven't really dug into git GUIs.
At times I have used ungit or git extensions (which, despite its name contains a full desktop application.
Today I use VS Code with a combination of Git Branch for visualization and Git Lens for the rest. Git Lens might need some configuration (I rarely use all the panes, but I use the interactive rebase tool from it as well as some annotationn features. For the visual rebase tool to work I had to configure VS Code as my git editor, but that is how I like it anyway.)
Again: try a few, find one that makes sense for you.
Jetbrains tools for example are generally good, liked by many and well though I understand, but still the git visualization (and a couple of other things) consistently manages to confuse me.
GUI vs CLI shouldn't be about which is a less confusing way of using git.
(Though, yes, magit is excellent, and there are very few tools which come close).
SourceTree: https://www.sourcetreeapp.com/
Windows and Mac. Free. Feels sluggish, but is also really dependable, the graph view is lovely and it covers most of the common things that you want to do - also, staging/discarding chunks or even individual lines of code is lovely. Oh, and the Git LFS integration, and creating patches is also really easy. And it gives you the underlying Git commands it uses, in case you care about that.
GitKraken: https://www.gitkraken.com/
Windows, Mac and Linux. May need commercial license. Feels like a step up from SourceTree, but i find that using this for commercial needs is a no go. If that's not an issue, however, it has a good UI, is nice to work with and just generally doesn't have anything i'd object to. IIRC it saved my hide years back by letting me do a ctrl+z for a repo after accidentally forcing to the wrong remote, so that i could fix what i had done (memory might fail me, was years ago), just generally feels intuitive like that.
Git Cola: https://git-cola.github.io/
Windows, Mac and Linux. Free and open source. Perhaps one of the more basic interfaces, but as far as free software goes, it does what it sets out to do, and does it well. I use this on Linux, whenever i want to have that visual feedback about the state of the repo/staging area or just don't feel like using the CLI.
TortoiseGit: https://tortoisegit.org/
Windows only. Free. Recommending this just because you mentioned TortoiseSVN. If you just want a similar workflow, this is perhaps your best option. Honestly, there is definitely some merit to having a nice file system integration, i rather enjoyed that with SVN.
Whatever your IDE has built in: look at your IDE
On any platform that your IDE runs on. Same licensing as your IDE. Some people just shop around for an IDE that they enjoy and then just use whatever VCS workflows that they provide. I'd say that VS Code with some plugins is really nice, though others swear by JetBrains' IDEs, whereas others are fine with even just NetBeans or Eclipse (Java example, you can replace that with Visual Studio or whatever). If you're working within a particular stack/IDE, that's not too bad of an idea.
The CLI: https://git-scm.com/
Windows, Mac and Linux. Free and open source. You'll probably want to know a bit of the CLI anyways, just in case. Personally, i'm still way too used to using a GUI since dealing with branches and change sets just feels like something that's more easy when visual, but the CLI has occasionally helped me out nonetheless.
Actually, here's a useful list of some of the Git GUIs: https://git-scm.com/downloads/guis
For example, did you know that there are some simple GUI tools already built in, git-gui and gitk?
When something goes wrong I just bork the whole repo and clone it again, then manually merge the last set of saved changes.
In some bad days I even miss Clearcase.
Easier? Who needs that? Soon then you will have common unlearned folk and peasants trying to use git. </snark>
They had the super obtuse git reset, that was four different things bolted together, so they fixed it by adding git restore, that does slightly different things, but you still need both...
Nix (and Haskell) has its warts, and undoubtedly a new system would avoid them (compatibility needs make some changes very challenging), but the fundamental difficulty remains because it is fundamentally different and solving a truly difficult problem set.