What activities can a 90 year do to stay busy doing the day, not electronically savvy or really can’t do crossword puzzles, will consider any automatic electronic activities
Audio books. Word puzzles (jumble, word find, etc)
Sudoku, word find puzzles, jig saw puzzles, solitaire, coloring. There are a wide variety of easy apps for these.
Audio books if she ever enjoyed reading. The key is to find a book she would enjoy listening to, especially in the past.
All good suggestions
If the person like plants or flowers, let them have a small garden in or outside to care for.