I've what I suspect is a daft question, but its answer has not yielded to my search abilities.
Are packages added to images built by the firmware selector via the drop down list option retained after a hard reset of the router (i.e., holding the reset button for 20 or 30 seconds), or does the router still revert to a bare minimum state after a hard reset?
For most devices which use squashfs as opposed to ext4 for a filesystem, you might be able to determine this for your system. The device page for your device may have specific instructions and more details. Table of Hardware
I don't have experience with what you are asking but I have an idea. I hope someone does give you your answer.
I think what comes in the image is in the squashfs and everything added after installation is in the overlay partition/filesystem. The squashfs is mounted on /rom/ and the overlay is mounted on /overlay/upper/.
So, I'm thinking that if the packages are found on /rom/ then they will survive a reset. If they are found under /overlay/upper/ then they will be wiped on a reset. If you figure out the regular path to binaries for your packages and then do an ls -l in an ssh session, simply prepend /rom to see if they are there and prepend /overlay/upper to see if they are there should determine if they would survive a reset. I can not guarantee it though.
As an example, I manually added a package for ccrypt which was installed to /usr/bin/ccrypt and it is in /overlay/upper/usr/bin/
root@R4S-wrt:/# which ccrypt
root@R4S-wrt:/# ll /overlay/upper/usr/bin/ccrypt
-rwxr-xr-x 1 root root 46668 Feb 20 2021 /overlay/upper/usr/bin/ccrypt*
root@R4S-wrt:/# ll /rom/usr/bin/ccrypt
ls: /rom/usr/bin/ccrypt: No such file or directory
I hope this info is useful.
EDIT: This should apply to other files such config files and system scripts etc
Very useful info spence. Thank you for taking the time to pull that together. I'll check those directories next time I update a device (I've not yet used the Firmware Selector), and of course I can confirm myself with a sacrificial hard reset after - that's what backups are for after all.
No. Nobody can. Nobody has written the code that supports this router. It would require people with skills for reverse engineering. Several weeks of work are needed in the best situation (if no proprietary drivers are actually needed).
This router is also apparently available in China only, and no public details are available about the chips used. Therefore, the chances of getting the code written are nearly zero.
In any case, discussion of new router support is not appropriate in this topic. The proper subforum is "For developers", and even then, it's only developers that start their work and collaborate. There is no way AFAIK to specifically request support for a particular unsupported router, short of hiring an expensive contractor - but this is done not through this forum.