9front, seemingly Plan 9's de-facto successor, is almost surely quirky, often whimsical, at times nostalgic. It might even be functional, depending on how you define that[1]. Is actively developed, has a vibrant community. Puts an interesting spin on how you lay out systems, but doesn't diverge much from the Bell Labs formula. I'd certainly recommend giving it a shot, for the UNIX-inclined.

[1] I've daily driven it back in high-school, for all that's worth. Wrote assignments in troff and all. Some people might be able to tell of less mundane success stories as well.

I tried Plan9 as a minimalist desktop. I soon realised that three-button mouse chording isn't doable in this decade, and wish someone had written a Platinum-like window manager to replace rio.

Forking Rio to create a Twm clone would be nice.

It's been somewhat done (there are a couple of forks out there, but nothing usable or maintained).

> I soon realised that three-button mouse chording isn't doable in this decade,

The scroll wheel on any wheelmouse is a button and you can click it as well as spinning it.

All wheel mice are also 3-button mice.

Try doing that on a trackpad--but if I wanted to use a mouse, the chording is too cumbersome.

On my work MacBook Air, I installed a FOSS app.

https://github.com/artginzburg/MiddleClick-Sonoma

Works well, but I miss the physical middle button on my Thinkpads.

The chording isn't really cumbersome, just unfamiliar. You get used to it quite quickly with a few tens of minutes of practice.

Writing high school assignments in troff puts your an ubernerd status, which I am slightly envious of ;-)

Plan 9's successor, is Inferno, which folks keep forgeting about.

Nothing's stopping you from making classic MacOS that OS – infinitemac.org is a tremendous website full of emulators with a large software collection and drag and drop file transfer! It has very good ergonomics if you just want to play around with it, throw some software you downloaded on to it, etc. When coding for the very early Mac, you just targeted a B&W 512x384 display.

The Macintosh Toolbox is a bit verbose, though.

There's this https://www.haiku-os.org/

Haiku lost the plot as far as I'm concerned when they didn't even try to support the Raspberry Pi as a target (where it would have been incredibly awesome). Right now the RISCv port is usable, but a lot of momentum was lost to the gods of fully open hardware...

Looks like they're working on it:

https://www.haiku-os.org/guides/building/compiling-arm64/

They have been working on ARM64, but avoided touching the Pi.

For me Ubuntu and Fedora give me nostalgia for Mac OS 10.5 and earlier. They remind me of that pre-iPhone era when software was shared via websites, when code signing and developer accounts hadn't become a thing yet, when the App Store was a radical suggestion, and before the OS became locked down with security and sandbox "features".

Yeah, you can still live in that era thankfully :)

The makers of Pico-8 just released a fantasy desktop called Picotron, and it's rather amusing. Not really a suitable daily-driver yet, though.

I've been having an absolute blast with it though! Don't think it's really geared to be daily drivable at all, just a fun environment to make stuff.

SerenityOS is probably your best shot, although it’s definitely not ready to be a daily driver yet.

Maybe uxn[0]?

0. https://permacomputing.net/Uxn/

If you have a RPi, RISC OS is an option.

AROS -- an AmigaOS-like environment -- can run in "hosted mode" on Linux or Windows environments, maybe Mac as well, in addition to standalone.

https://www.aros.org

Note that because it's an API-compatible reimplementation of AmigaOS, it's not really a "fantasy OS". Hosted mode is rather a tool for serious OS development. Nevertheless, it's much more like a modernized retro Amiga than it is any extant DE for Windows/Linux/Mac.