Back when I had to use a windows vm just did

qemu ... -net user,smb=$HOME/

then in the windows vm just type \\10.0.2.4 into file explorer. Does that not work?

man qemu says:

              smb=dir[,smbserver=addr]
                     When using  the  user  mode  network  stack,  activate  a
                     built-in  SMB  server  so that Windows OSes can access to
                     the host files in dir transparently. The  IP  address  of
                     the  SMB server can be set to addr. By default the 4th IP
                     in the guest network is used, i.e. x.x.x.4.

                     In the guest Windows OS, the line:

                        10.0.2.4 smbserver

                     must be added in the file C:\WINDOWS\LMHOSTS (for windows
                     9x/Me)  or C:\WINNT\SYSTEM32\DRIVERS\ETC\LMHOSTS (Windows
                     NT/2000).

                     Then dir can be accessed in \\smbserver\qemu.

                     Note that a SAMBA server must be installed  on  the  host
                     OS.

Another way is to setup Spice and use a webdav daemon in Windows to transfer files over Spice folder sharing.

You could also just RDP to the machine which is probably the easiest.

The simplest would just be to scp files to and from Windows. Like in powershell do scp -R yourusername@10.0.2.2:~/path/stuff output_dir to get files from Linux.