The FN version of the 98 Mauser was probably the nicest of all the Mauser actions. If yours is a commercial sporter action, then you have done well.
The FN commercial actions were used by Husqvarna in Sweden. The Swedes did not mess about. They built good rifles.
Now I cannot test fire that rifle for you. That's the only way to determine how accurate it is.
But it has a good action and assuming the barrel and stock were installed properly, you have the basis of a decent shooter. Can you find out who built the rifle? And if possible you want to have the gun looked over by soomeone who knows rifles. What kind of barrel does it have and how much does the seller want?
There are lots of accessories for Mausers. Lots and lots and lots. As many as fleas on a dog.
Fluffy