I recently realised that one thing I’m really sucker for is when Harry fucks off to build his own island or country, or GOT xovers where he takes over and builds his land up.

that got me thinking - are there books or series focused on this topic? I dont mean the political intrigue and power struggles a la GoT, but actually focused on building something up - be it MC dropped off nowhere building up their life, person building a village or something like that? Proper published books?

 

I've looked for this before and never quite found anything much.

Dragonsdawn is the closest I've come across (the prequel to Anne McCaffrey's Pern series featuring sci-fi colony settlers).

https://www.goodreads.com/book/show/465904.Dragonsdawn

It's a bit of a broader view than you might have been looking for, but Adrian Tchaikovsky's Children Of Time is essentially the chronicle of an entire civilisation as they evolve from primitive non-sentient animals (spiders) into a spacefaring civilisation. It's a fantastic book and I can't recommend it enough even if it wasn't exactly what you were looking for.

https://www.goodreads.com/book/show/25499718-children-of-time

For a more literal interpretation of building something, there's Ken Follett's The Pillars of the Earth about the construction of a medieval cathedral.

https://www.goodreads.com/book/show/5043.The_Pillars_of_the_Earth

 

The historical novels by Rebecca Gablé might be something for you? They are originally in German, but two of them are available in English as well:

Scarlet City: Apprentice/Rise/Empire follows the life of a London cloth merchant in the 14th century. It's an amazon audio drama.

The Settlers of Catan is a novel following the idea of the game of the same name - a bunch of Vikings land on a remote island and build up anew there. (IIRC the creator of the game literally approached her to novelise it.)