Upgrading the kernel is generally not difficult as long as you follow the instructions Aravisian provides in the thread above. The biggest risk is that you could run into video drivers that don't have DKMS support for that kernel yet, which it sounds like you've experienced from your post above. (DKMS is what lets a driver with kernel modules work across multiple kernels.) The second link I'm going to provide below may help you in such cases.
More resources that might be of use to you, given your described troubles.
This howto explains how to very easily strip all Nvidia drivers from your system before installing the newest packaged versions. These versions are not straight from Nvidia, they're prepped by package maintainers to easily install on Ubuntu based distributions. (Zorin is Ubuntu based.) Because of that, you won't find the newest release from Nvidia immediately, and you could potentially have DKMS issues if you're upgrading your kernel to bleeding edge. The only solution there is to wait.
This guide explains how to install Nvidia's drivers using the installer straight from Nvidia. The process is considerably more involved. I wouldn't call it hard, but there are a fair few steps, and it will require updating the version of gcc on your machine. That's not hard either, and there's a link to a tutorial on that in there, but again, lots of steps. (You'll only have to update gcc once, barring a reinstall of your system.) I personally don't recommend this unless you're someone who really wants to have the latest driver immediately, and is comfortable with getting a little more hands on, but this IS what I do personally.
As to the question in your subject: Upgrading the kernel is worth it if and only if you get something out of it. Having the highest version isn't an end unto itself (unless you just really like maintaining your own stuff), but there have been a number of kernel improvements to CPU and hardware support since 6.8. I personally update my kernel and video drivers by hand, and I've only been a Linux user for a year and a half or so, some dabbling in the 90s notwithstanding.