Hey guys! Could use some insight from you lovely folks!
I don't know if this is the right place to post this, so apologies to admins if not.

I'm currently worldbuilding a steampunk fantasy novel, based on Scandinavia and set in a time where Scandinavia (Sweden particularly) was very influenced by French culture historicaly (in the 1700s particularly). I haven't started writing it at all, because I want to get an understanding of the world and the characters first, but this is the premise so far. As a Swedish person, I thought it would be fun worldbuild based on what I know and in a steampunk fantasy setting.

Brief Premise:

"Keliana would rather die in the line of fire protecting her charge than go back to life in the Rookery, where if the breath of drunken bar patrons don’t kill her, disease surely will. So, when the Crown Prince is kidnapped by a group of rogues, she has no choice but to team-up with an imprisoned watchmaker on trial for murder, who claims to know where they’re going.

Gus is a watchmaker’s apprentice who spends his day slaving away for pittance, while looking after his father who is losing his mind to memories of ancient battle. One day, Gus finds the shop broken into and the old watchmaker dead. Suddenly, all fingers are pointed at Gus and he finds himself accused of the murder. Just before his arrest, Gus is able to retrieve his boss’ latest project; a watch that was supposed to be a gift for the crown prince for his 18th birthday.

When Gus hears about the crown prince’s kidnapping, he realises that he’s able to help find the prince and clear his own name, but to do so he has to work with a royal guard who’s set on doing things her way or no way.
Keliana doesn’t trust anyone, but she has to learn to trust Gus or the life she’s worked so hard to build for herself will be over and she’ll be disgraced.

What neither of them realise is that there’s a bigger endgame and that the watch is the key to revealing secrets some people are very keen to keep buried."

This is all very vague at the moment, but I know I want the watch to be important somehow and I was thinking maybe it could be designed as a sort of cambera obscura with a pinhole and a map inside, so it looks like a normal watch, but some sort of magic or magitech makes it so it shows where you are on the map. The closer you get to where it is taking you the more the map will shrink.

I guess my main conundrum is what lies at the centre of the map and why would it be important to our characters? I had vague ideas of using something combining magitech/norse runemagic, but this is all the very early stages so I'm just floating these ideas around.

I'm figuring out how the rune magic works. I don't want everyone to be able to do it, but I want I wanted it to be tied into the tech somehow.

The vibe I want is like a classic adventure like Jules Verne/the Mummy/Disney's "Atlantis", because I think that's really fun. So I'm looking for any kind of ideas and some discussion.