Accessing linux partitions (including BTRFS) from WSL2

(as documented) Insert your USB stick, hard drive, sd card, what have you, then run

GET-CimInstance -query "SELECT * from Win32_DiskDrive"

You will get result like

DeviceID           Caption                          Partitions Size          Model
--------           -------                          ---------- ----          -----
\\.\PHYSICALDRIVE0 WDC WD30EFRX-68EUZN0             1          3000590369280 WDC WD30EFRX-68EUZN0
\\.\PHYSICALDRIVE4 SanDisk Cruzer Switch USB Device 2          16006394880   SanDisk Cruzer Switch USB Device
\\.\PHYSICALDRIVE3 NORELSYS 1081CS0 USB Device      2          31914086400   NORELSYS 1081CS0 USB Device
\\.\PHYSICALDRIVE1 Hitachi HTS543225L9A300          1          250056737280  Hitachi HTS543225L9A300
\\.\PHYSICALDRIVE2 WD_BLACK SN850X 2000GB           4          2000396321280 WD_BLACK SN850X 2000GB
\\.\PHYSICALDRIVE5 NORELSYS 1081CS1 USB Device      0                        NORELSYS 1081CS1 USB Device

Then, mount to WSL:

wsl --mount \\.\PHYSICALDRIVE5 --bare