CAN YOU MAKE A WSL (UBUNTU) FILE SYSTEM VISIBLE FROM WINDOWS FILE EXPLORER?

Yes, in powershell, do (for example)

..user > subst W: '\\wsl$\Ubuntu-20.04\home\username\'

And you're in business. But, yes, I know what you're thinking - you don't want to do this manually. 

You want to fire up WSL TTY (mintty) and have this DONE for you!

In your Ubuntu filesystem, maintain a file ending in a .ps1 extension and containing :

subst W: '\\wsl$\Ubuntu-20.04\home\analog\'

Then, in your .profile, just have :

powershell.exe -File /path/to/subst_cmd.ps1

(FYI, Thanks Thanh Phu, do delete this mapping, you'd do subst W: /D )

And you're through. Now, here's something trickier :

Without ever leaving WSL, how would you get Windows Firewall to allow communication between WSL 

and the X-server you set up (follow Thomas Ward's excellent page to set up vcxsrv)

The answer : 

Put this command in a file somewhere on windows (not Ubuntu) :

Set-NetFirewallProfile -DisabledInterfaceAliases "vEthernet (WSL)"

Then, all you do is :

powershell.exe -Command "Start-Process powershell.exe -ArgumentList \"-File C:\path\to\ps_fw_setting_WSL.ps1\" -Verb RunAs"

Which is something you could stick in your .profile