I am going to upgrade my Linksys WRT routers from 19.07 to 19.07.2 via sysupgrade.
Do I need to perform a full backup of all the addtional packages and configurations I have on 19.07, or as it is a minor upgrade, do all the packages remain as they are? I mean, by cheking the "maintain configuration" option on the sysupgrade.
I know from 18.06 to 19.07 I had to start from scratch (openvpn, dyndns...), but I am not sure if it is needed from 19.07 to 19.07.2.
On every upgrade the user installed packages will not be preserved. You can check the tickbox to keep the configuration (just make sure that configuration of all extra packages is included), and you can do it for releases within the same major version (that is from 19.07 to 19.07.2)
To reinstall the packages after an upgrade, I am using this script. Take a backup before and run it after the upgrade again to restore the packages.