How much time does it take to get it working?
It depends on your knowledge of electronics, how fast you work, and how many bells & whistles you put in. The moment you get on the aesthetics wagon, drilling holes for meters, switches, cable plugs and sockets to make it look good, the hours go quickly. A barebone system should not take more than two full days, if all parts are available and you know your way around a toolbox.
You will probably spend more time than you expect on assembling this, and probably a little extra money as well, but on the other hand you will get a lot of unique knowledge, which will benefit you and your family/friends for life. That is a reward in itself. It is also pretty great when you got the system working and you did the job yourself. And you will be able to assist others in building their systems and helping their loved ones, too.
Note: If you are ill, suffering from brain fog or cognitive impairment, chronic fatigue or any other serious condition, you must seriously consider if this is a project suited for you. Have you got the energy and the mental focus? Is there someone you can ask to build it for you? Or consider an off-the-shelf system.