Idea for a large click to move open world

Looking to create a game with a large open world that you click to move around in. Similar to that of the game Kenshi. In that game you can click on the entire opposite of the map and your character will find its way there. I know Kenshi uses Havok AI system which is apparently so expensive you have to call their sales team to get a quote on it.
I plan to have player creatable buildings in a similar vein as well that will have their own navmesh requirements. The world I’m envisioning will likely be close to 30,000x30,000 units.
After playing with both the built in unity nav system and A*Pathfinding layered grid graph is my best bet as it works best with my building models. I tried a few different ideas like generating the entire grid and using the procedural mover. Generating the entire grid is probably not a viable option as the sheer scale will consume a great deal of memory. The procedural mover would be a lot more viable but it doesn’t let you seem to set a destination outside the current procedurally generated grid.

I haven’t tested the idea yet, but i was wondering if perhaps a viable strategy for long distance travelling would be to manually plot connected waypoint nodes within X distance of each other so that one would always appear within the procedural grid and if the destination wasn’t within the procedural grid, it would look for one of those waypoints. A sort of meta pathfinding system. This would allow for neat functionality such as having prebuilt roads be a more preferred destination for travelling if i laid out the waypoints along the roads. Maybe a weighted preference value for each waypoint.

Otherwise, I’m running out of options because I’ve spent a week and if I can’t nail this down I might just give up on this project altogether.

That’s a huuge map.
I have heard users with 10km * 10km maps using the recast graph. But at 30km*30km it would probably be too much. You would also likely start to run into floating point errors at those scales.

The procedural grid mover can work if you only need pathfinding in a small region around the player.

You could definitely do something like this. You probably want to read up on hierarchical pathfinding. This is not implemented in this package, but you could possibly create it yourself using a point graph and forcing a pathfinding request to use only that graph.