@All
Soo, after derfs with help of modern AI magic created Virtio9PFS-handler :
https://github.com/derfsss/Virtio9PFS-handler (so you have ability to use shared directories and not the sucky fat-stick-way where you need to reboot always to see changes), and after smarkusg confirmed that it works on linux and macos, i tried to make it work on windows too, with pegasos2 emulation, just to realize that it has no -virtfs (p9) used for those shares..
First idea was to use WSL2 build, which i did, just to realize that because of layers in between it's still visibly slower than native win32 build of qemu. So no go.
Then doing some research to find out that there were some unofficial patches to make virtfs working on native windows targets too, but for older versions of qemu. So i took latest 10.2.1, and started applying those patches, firstly some older ones, then newer ones, but of course conflicts and stuff, but in the end succeeded, and TADAM:
(click open in new window for full size):

And it indeed works! Everything ultra fast, everything immediately refreshes and can be seen in realtime. Speed awesome, just gigabytes per second, and i can forget now as a bad dream this fat32-ugly way.
So thanks to derfs (and of course those AIs who can help us now), to smarkusg for tests, and for somebody's patches for win32.
PS. The funny thing is, once i made it all work, i found out that on github there is one man who is doing exactly the same, and made ready to use builds with integrated virtfs-p9 patches, damn! But at least i spent a day for learning purposes about qemu :)
@derfs
You may want to change readme saying that for windows you need unofficial builds with virtfs support, which can be found on:
https://github.com/arixmkii/qcw/tags , or patches from
https://github.com/arixmkii/qcw/tree/main/patches/qemu can be applied manually when building qemu from sources.
Line for running same as smarkusg show:
-fsdev local,security_model=mapped,id=fsdev0,path=D:\SHARED -device virtio-9p-pci-non-transitional,id=fs0,fsdev=fsdev0,mount_tag=SHARED
simple
-virtfs local,path=D:\SHARED,mount_tag=SHARED,security_model=mapped
didn't work.. So seems transitional, legacy didnt works , while modern VirtIO 1.0 works for pegasos2?