I'm not a programmer, well, not any more, anyway.
I did re-program the Commodore 64 but that was a lifetime ago.
However if I were going to write an OS today to handle all of today's BS, it would probably look a lot like Win-11.
Not so much in looks, because I never did understand that big Blue Thingy, which for me is "
Gone in 60 seconds!",
but for it's malleability. It's like the modeling clay I played with as a child. You can mold it into what you want.
I'm running Windows 11/Pro/64 on a PC that is so old, if it were any older it would be running on Steam.

I burned the Window 11 ISO to a Flash Drive using the latest ver. of '
Rufus', and it took out all the nasties from the ISO I downloaded. No conditions, no TMP, no security questions, no insistence on a MS Account, and no BS!
And, it installed like a dream! Fastest install since DOS 6.22.
This old PC (bios date 2008) is just Humming' along, with 16 GB of ram, a 500GB SSD and an old motherboard from EBay.
It DOES NOT meet the requirements set forth by Microshaft, for the install if Windows 11.
On a similar PC, I've run every OS since ME, and Windows 11 is running the fastest and the smoothest.
I just could'nt ask for more. She boots up in about ten seconds, and shuts down in five. PERFECTOMUNDO!