I have made similar devices (automated fillers for small production businness, like soap or hot wax fillers and other liquid dispencers) and can do it.
In my opinion, RPi is not the best option for this project if you are not planning to use the same RPi for other tasks in the same time. First of all, 7" touchscreen for RPi is not widely available and expencive. When your user interface is static and no other tasks (for example, web-browsing or displaying of big and not static set of the images) is necessary - it is overkill. Using of HDMI display with touchpanel is also enough expencive and will not provide any pros for this particular task.
In the same time, there are Nextion displays that are perfectly suits for tis task. In that case, the whole task can be done with Arduino Mega board. It is cheap, widely available and also there are a lot of industrial versions of that controller for a reasonable price (however, with a good power supply any board will work).
One of the pros in case of using Nextion: you can use your own graphics (images) and change (refresh) it anytime without changes in the code.
However, I can make it with RPi if you have some reasons for it
Please feel free to contact me in chat for discussion.
I have great experience in creation, modification and remote debug of the code for microcontrollers
I have made more than 200 projects on different freelance stocks and have more than 30 years of experience in programming and electronics.