There were no problems during install. Just install Ubuntu on a USB device with Unetbootin or Rufus (Unetbootin can keep the existing data on your USB device and just add the install-image as extra folders).
But these are the optimizations I did after install:
Optimization for installation of Ubuntu On toshiba portege z20t-c-12j
base install of missing applications
echo ttf-mscorefonts-installer msttcorefonts/accepted-mscorefonts-eula select true | sudo debconf-set-selections
SYSTEMLANG=de
apt install unp audacious gimp gimp-help-de pidgin pidgin-otr haveged language-pack-$SYSTEMLANG language-pack-$SYSTEMLANG-base firefox-locale-de hunspell-$SYSTEMLANG-$SYSTEMLANG libreoffice-l10n-$SYSTEMLANG thunderbird-locale-$SYSTEMLANG inkscape fail2ban ncdu ccze dfc screen tmux sshfs keepass2 workrave dolphin chromium-browser krusader krename kompare kate p7zip audacity ttf-mscorefonts-installer ubuntu-restricted-extras etckeeper xfce4-goodies redshift meld htop atop fonts-ubuntu-font-family-console gnupg2 picard w3m curl wine make gcc g++ unzip gawk bzip2 yakuake onboard neovim tree psensor hardinfo kdiff3
Get rid of Lenses
apt remove unity-scope-chromiumbookmarks unity-scope-colourlovers unity-scope-devhelp unity-scope-firefoxbookmarks unity-scope-manpages unity-scope-openclipart unity-scope-texdoc unity-scope-tomboy unity-scope-video-remote unity-scope-virtualbox unity-scope-yelp unity-scope-zotero unity-lens-music unity-lens-photos unity-lens-video
backgroundimages
https://askubuntu.com/a/1145869/34298
Keyboard-layout
Configure Caps Lock as AltGr and Arrows like in vim
fix nodejs
snap install --classic --edge node
sudo ln -s /snap/bin/npm /usr/bin/npm
snap install atom --classic
fix scrolling in Firefox
https://askubuntu.com/a/994483
in case you use KDE or Kubuntu
Plasmashell High CPU Load Fix - Plasma 5.15 KDE on Kubuntu 19.04
fix default app okular:
https://www.ryananddebi.com/2014/09/29/linux-fixing-pdfs-opening-in-gimp-in-firefoxzotero/