Overall, are any Chessbase products worth buying, for someone who plays a mix of daily and rapid and is not very high rated but keen to study and improve?
Yes, but unfortunately you would have to start with the base program, which is €130, and it's only half-complete unless you also buy Fritz, which is €80.
That being said, some of the Fritz trainers are €30, and you don't need ChessBase itself to use them. You can use them in either CB or Fritz. In fact, the latter has a few kludgy additions to it so that it can function independently of the former.
Chessable is a good alternative, but beware the sales tactics. Some of their material is GM-level, and they'll push it on beginner and club players.
Overall, are any Chessbase products worth buying, for someone who plays a mix of daily and rapid and is not very high rated but keen to study and improve?
The series of Daniel King "Powerplay" for lower rated players can be useful. But you can also check the products at Chessable or Aimchess.