Is there a plugin or native setting that would allow me to set certain topic or category to be ignored for everyone (so that not everyone has to do it for themselves but still be able to unignore if they wish)?
I would like to let users post in certain topic / category but without triggering "unread" status (like off topic category etc.)
Is there an option to create charts based on specific data? I'd like to try create kind of training diary, where I could see progress of specific day/weeks/months of training with some interactive charts, is it doable in NodeBB?
You can do pretty much anything you want if you're willing to put in the work to make a plugin. Without that, though, no there's no way to configure NodeBB core to do that.