I found the plugin and developed a solution with Kovid Goyal's help as detailed in
https://bugs.launchpad.net/calibre/+bug/2131923
Here's from that (invalid) bug report:
I found a solution. Got the current source tarball from
https://calibre-ebook.com/dist/src (ref
https://manual.calibre-ebook.com/dev...tting-the-code). Searched the unpacked tarball for 'PocketBook Touch Lux 2'. Found in src/calibre/devices/misc.py. Modified it as shown in this diff:
Code:
523,524c523,524
< name = 'PocketBook Touch Lux 2'
< gui_name = 'PocketBook Touch Lux 2'
---
> name = 'PocketBook Era'
> gui_name = 'PocketBook Era'
535c535
< SCAN_FROM_ROOT = True
---
> SCAN_FROM_ROOT = False
Set envar CALIBRE_DEVELOP_FROM (ref
https://manual.calibre-ebook.com/dev...nt-environment) and ran calibre. When the PocketBook Era was plugged in it was reported as a PocketBook Era (cosmetic) and the Device tab displayed only books in the Books directory (as wanted).
When the PocketBook Era was first connected by USB it had USB vendor ID 18d1 and product ID 0001. The
https://the-sz.com/products/usbid/in...8D1&p=0x0001&n shows those indicate a Google "Onda V972 (storage access)". When the PocketBook Era screen's PC LINK was pressed those changed to USB vendor ID fffe and product ID 0001.
Vendor ID fffe is probably not official (= assigned by
https://www.usb.org) because it does not appear in
http://www.linux-usb.org/usb.ids, appears in
https://usb-ids.gowdy.us/read/UD?restrict=f without assignment and is "Nothing found" at
https://the-sz.com/products/usbid/in...FFFE&p=0001&n=