I have a lot of apps on my N9, many now just as souvenirs in a "misc" folder until I need the space. Many no longer work but if I used to like an app, I feel sad just tossing it, so instead I move it to Misc folder. All those that don't require internet, obviously, should still work. Like, I have a calculator collection, for example, and of course those work. Most that do require internet probably do not work anymore. You just have to test stuff you are interested in. Go here for apps:
https://openrepos.net/content/basil/about-openrepos

And read the wiki about using N9 nowadays, tho I find it incomplete and sometimes inaccurate (it tells you how to install emoji font but not how to fix serious problem with text from others that have emoji vanishing without notice; it says gmail does not work but that's not true, you just have to allow "low security" apps to access your email):
https://wiki.maemo.org/Resurrect_your_N9

But this is kinda off topic, so go to one of the software forums (like games, etc) to discuss or research more, here:
https://talk.maemo.org/index.php

It is still nice using the N9 for someone who has had it for a long time, but probably hard for someone new to it. I had years to slowly move broken apps to Misc folder (or delete). It would not be fun to do that within a short time. Still, much better than, say, a flip phone, if you want digital minimalism.

Enjoy your N9!