That’s what I do. I have a bunch of .desktop files that just open Firefox in kiosk mode to whichever website I want, and a bunch of .PNG files to make them look like apps. I installed them system-wide.

I’m a pretty big KDE Stan but I decided to give Gnome a go since Plasma Bigscreen is virtually impossible to install for a normal user at the moment. Its not perfect but it gets the job done, and I love the basic parental controls it has. Still absolutely awful in terms of settings though.