My mate has a Note 9 and I had a play with it. With most apps the stylus only replaced my fat fingers so with a stylus it's a bit easier to click and select on the screen. Maybe handy when wearing gloves? Some apps are stylus enhanced or specially made for a stylus, but I don't think there are any navigation apps. My mate is using the stylus to write notes and make annotations on photos and screen dumps. Best feature, the stylus is also a remote control for the camera. The camera on the Note 9 is one of the best you can get at the moment. It's a big phone, a bit heavy and battery live (depending on pictures taken) can be up to 4 days when in flight mode.
[edit] The Note 9 has the same camera as the Galaxy 9, only the software is a bit different. Note 9 is using AI software which can be disabled.
For a lighter and cheaper option with a good camera, the Google Pixel 2 is very good and a bit cheaper now the Pixel 3 is available.
Regarding 5G, in my opinion, it's useless unless you want to stream 4K / UHD movies and download a lot of stuff fast. It will only work in the CBD anyway and drain your battery. I've got my phone always on 3G which is fast enough for most things and will save a lot of battery life. When set to automatic network, the phone will still be scanning for a better option, switches to 4G, back to 3G, scanning etc. You get the point
When walking most of the time my phone is in flight mode anyway.