Start with 19.1 and show broken flatpak, show updating to 19.2 fixes the platform error
Things to do on a fresh install
Overview of stock default apps
VirtualBox install and use
adding themes, tweaking css, setting user-logo, using dconf-editor to tweak title-bar font +++ generally scaling the ui-items for disabled people // adding launchers (right-click - menu -> panel,desktop // creating one using add-launcher tool // creating one using desktop-files)   // extending file-manager by adding scripts // ...

How to disable systemd-resolvd and install/use pi-hole
How to use mint backup tool, both portions of it.
How to know if snaps functional on Mint?
How to track down an app crash with strace
How to get started with Python 3 doing Hello World
How to change application associations
How to add another user and make it available
How to make trim cron daily instead of weekly
How to boot nomodeset for video problems
How to install, configure, and work with phpmyadmin / mariadb

DONE - How to boot init=/bin/bash and recover your forgotten user password
DONE - How to update the kernel to a higher branch
DONE - how to take a screen shot and post it to imgur.com
DONE - HowTo disable and enable Printing -> sudo systemctl disable cups && sudo service cups stop
DONE - how to set the grub default timeout to something reasonable