Such filters are widely used in places such as Iran and China, and could be used for a home network. The problem with filters is that they aren’t clever enough. For work, I had to research the legal status under halachah of child born to a woman who had been become pregnant while being help prisoner, and the filter saw a naughty word (R-A-P-E) and blocked the search. If you block the word A-B-O-R-T-I-O-N, you’ll block research about pro-life groups, or mutual funds that don’t buy stock in companies that make a living by providing the drugs and tools needed.
The best filter is the user having sufficient intelligence and yeras shamayim not to look at what they know they shouldn’t look at, and in a home or office or library, to have all computers facing “out” so the screen is visible (if you need privacy, you probably shouldn’t be looking at it).