Only freelancers from European Union: Configuration of VNC (screen sharing) on LINUX

We use mini-PCs (Intel celeron or i3 processor) running on Kubuntu 18.04 LTS x64. We want to configure a VNC functionality (screensharing) in the following form: - the user can activate VNC on the host with a simple measure (ideally clicking on a icon on the desktop) - the client (on another computer) can start VNC on his end also by clicking on an icon - the client has to enter a password which can be changed on the host with a simple measure We would like to test 2 clients: a) another LINUX mini-PC b) a Android tablet We would send to the freelancer 2 mini-PCs and a Tablet for installing and testing the software. At the end of the project we would collect the PC and the tablet again. The project should be possible to fullfill with out-of-the box standard Linux functionalities. If you use third party software please let us know the licence fees per installation in advance (when you bid for the project). In order to ship the equipment back and forth (without issues with customs) we only accept bids from the european union.