Very little to know really. It is a marvellously simple bike.
The usual ‘improvements’ are:
Free breathing air filter.
Better spark plug.
Replace the starter / ignition relay. I replaced all of them, as decent Bosch ones are not a whole bucket of cash.
Sintered brake pads.
Adjustable side stand.
Chain oiler.
Some bods go on with big bore kits / cam / exhaust etc but the bike is 25 bhp, so really what monster power is anyone going release? If you want a more powerful bike…. Go buy one. Maybe an exhaust but really that is more to shed weight than add power.
Luggage will always be a personal taste thing.
No doubt there are screens, seats, lights and all sorts of other bits and pieces available.
Mine seems to lose (ie. it just stops working) its front brake light switch for some reason I cannot work out.