Hello michaa7,
yes, your new, free life with siduction starts straight from booting the live system.
Not only new packages become part of your install, also system settings from /etc or user settings from /home/* do survive the install. This is a great opportunity to check if your preferred application works. And if the test succeeds, then your effort is saved and it is part of the install. On the other hand, if you fail and break the settings, then you better void that try and reboot a clean live system before you proceed with the install.
Another option is updating the installer before installing (when updates are available). This allows for bugfixes without a fresh release. You can use the "update"-Button in the installer or do:
apt-get update && apt-get install sidu-installer sidu-base pywwetha
If you like you even can play a little more and boot to the multi-user.target (by adding a "3" at the boot prompt) and modify settings or install additional drivers before continuing to the graphical.target "systemctl isolate graphical.target". You can change the KDE cursor theme from sharpdot to Adwaita with "update-alternatives --set x-cursor-theme /usr/share/icons/Adwaita/cursor.theme". You can add contrib and non-free sources and install the virtualbox-guest-dkms + virtualbox-guest-x11 (or qemu-guest-agent). In the past i have successfully installed the nvidia-driver after blacklisting the nouveau module (beware, AMD Radeon is special). Anything goes that doesn't require reboot, and lucky linux users don't need reboots (mostly).
greetings
musca
[Edit. and marked solved]