Can’t read/write via `dd`: got /dev/disk2: Permission denied (to Physical device)

I can't do anything via dd with my Physical devices agreed.
I can only work with partitions like disk2s1, but can not read from whole disk like disk2.
Can't find where is the root of problem.

Steps:

1. Check disks: diskutil list
2. Unmount: diskutil unmountDisk /dev/disk2

Then

$ sudo dd bs=4m if=/dev/disk2 of=~/Desktop/PiOS_full_root.img
dd: /dev/disk2: Permission denied

What causes this problem? why dd sends this error from sudo

there are similar topics around. What've tried, but doesn't works:

• “dd: /dev/disk4: Permission denied” error when making LiveUSB on Mac OS X
  

and many others. nothing is helps.

• I check system preferences and gave full disk access to iTerm2 (doesn't help)
• unmount via diskutil unmountDisk and diskutil unmount
• Change USB ports (many people said because of the physical lock of sd card.
• change disk / rdisk naming – result the same
• Lock\unlock state doesn't affect it (it's microUSB, put without adapter into the microsd slot)

Any suggestions, what to check, and how to fix it?

Here is the log:

~ ❯ diskutil list                                                                                                                                                                                 
/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *500.3 GB   disk0
   1:                        EFI EFI                     314.6 MB   disk0s1
   2:                 Apple_APFS Container disk1         500.0 GB   disk0s2

/dev/disk1 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +500.0 GB   disk1
                                 Physical Store disk0s2
   1:                APFS Volume Macintosh HD - Data     437.8 GB   disk1s1
   2:                APFS Volume Preboot                 80.6 MB    disk1s2
   3:                APFS Volume Recovery                528.5 MB   disk1s3
   4:                APFS Volume VM                      1.1 GB     disk1s4
   5:                APFS Volume Macintosh HD            11.2 GB    disk1s5

/dev/disk2 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *15.9 GB    disk2
   1:             Windows_FAT_32 boot                    268.4 MB   disk2s1
   2:                      Linux                         15.7 GB    disk2s2


 ~ ❯ diskutil unmountDisk /dev/disk2                                                                                                                                                               
Unmount of all volumes on disk2 was successful

 ~ ❯ sudo dd bs=1m if=/dev/rdisk2 of=~/Pi_Backup.img
dd: /dev/disk2: Permission denied

 ~ ❯ ls -lhdO /dev/disk2                                                                                                                                                                           
brw-r-----  1 root  operator  -   1,   9 Jul 11 17:39 /dev/disk2

Update: another interesting thing: I chack disk in disk utility -> Get info -it's not writable!

But if I mount boot partition disk2s1 – I can write there!