I wish either of those systems had the same hardware & software support. I’d swap my desktop over in a heartbeat if I could.

Why should everything pretend to be a 1970s minicomputer shared by multiple users connected via teletypes?

If there's one good idea in Unix-like systems that should be preserved, IMHO it's independent processes, possibly written in different languages, communicating with each other through file handles. These processes should be isolated from each other, and from access to arbitrary files and devices. But there should be a single privileged process, the "shell" (whether command line, TUI, or GUI), that is responsible for coordinating it all, by launching and passing handles to files/pipes to any other process, under control of the user.

Could be done by typing file names, or selecting from a drop-down list, or by drag-and-drop. Other program arguments should be defined in some standard format so that e.g. a text based shell could auto-complete them like in VMS, and a graphical one could build a dialog box from the definition.

I don't want to fiddle with permissions or user accounts, ever. It's my computer, and it should do what I tell it to, whether that's opening a text document in my home directory, or writing a disk image to the USB stick I just plugged in. Or even passing full control of some device to a VM running another operating system that has the appropriate drivers installed.

But it should all be controlled by the user. Normal programs of course shouldn't be able to open "/dev/sdb", but neither should they be able to open "/home/foo/bar.txt". Outside of the program's own private directory, the only way to access anything should be via handles passed from the launching process, or some other standard protocol.

And get rid of "everything is text". For a computer, parsing text is like for a human to read a book over the phone, with an illiterate person on the other end who can only describe the shape of each letter one by one. Every system-level language should support structs, and those are like telepathy in comparison. But no, that's scaaaary, hackers will overflow your buffers to turn your computer into a bomb and blow you to kingdom come! Yeah, not like there's ever been any vulnerability in text parsers, right? Making sure every special shell character is properly escaped is so easy! Sed and awk are the ideal way to manipulate structured data!

AmigaOS was the pinnacle of personal computing OS design. Everything since has been a regression. Fite me.

https://cosmoe.org/

It would not solve the ABI problem, but it would give at least an opinionated end to end API that was at some point the official API of an OS. It has some praise on its design too.

I regularly install HaikuOS in a VM to test it and I think I could probably use it as a daily driver, but ported software often does not feel completely right.

There's a lot to like about BSD, and many reasons to prefer OpenBSD to Linux, but ABI backward-compatibility is not one of them!

One of Linux's main problems is that it's difficult to supply and link versions of library dependencies local to a program. Janky workarounds such as containerization, AppImage, etc. have been developed to combat this. But in the Windows world, applications literally ship, and link against, the libc they were built with (msvcrt, now ucrt I guess).

(OK, I have some experience with vendors where their latest month-old release has an distro support release where the most up-to-date option is still 6 months past EOL, and I have managed to hack something together which will get them to work on the newer release, but it's extremely painful and very much not what either the distros or the software vendors want to support)