Timekpr-nExT is graphical parental control tool for Linux, useful if you want to limit child activity on a computer. The application, which uses Python / GTK3, works with multiple desktop environments, including GNOME, Xfce, Cinnamon, KDE Plasma, Unity, Deepin and Budgie, under both X11 and Wayland.

Source: LXer – Timekpr-nExT Is A Linux Parental Control Program For Limiting Computer Usage