Grippers are only good if you want to get better at grippers. Grip strength is so specific and if you are talking real world transferability grippers are probably the worst. IMO if you want something that actually transfers and that you can still use at a desk and that offers some variety get one of these https://www.sportgrips.com/product/grip-twister/

Then for extensors get some rubber bands.

Source: I've been doing grip strength training for over a decade, my basement is completely filled with grip training tools. So, trust me bro. Honestly though, bouldering is probably the best, can't do that at a desk though.