Hi @bjorn @dogboydog
I am interested in this project , opening this tab for all communication and discussion regarding this project at one place.
Here are few things which I have already done :
→ Built Tiled from source using QT6 + Qbs on macOS (my Os for this project)
→ Have navigated real build issues and resolved them on my local machine
→ This give me benefit to run and compile and also see changes locally.
Next I have started to have fun with features 
though I replicated one of the bug locally and have raised pr for that as well Fix spacebar panning not working after focus leaves the map view by Oval17 · Pull Request #4338 · mapeditor/tiled · GitHub
Then found a very minor issue have raised a proper issue in issues tab + pr as well for that
What I am planning on net is to continue exploring (as I am really having fun with the project besides anything )
Talking about project we have the following features to be build for this project enhance world editing
1→ world grid
2 → Default World
3 → Resize via Drag
4 → Create delete maps
5 → shared map view
I have started to go one by one to get deeper understand for the codebase and what all changes will be required.
Would love to continue my discussion for this project here and will welcome other contributors as well to help and give there inputs
Thanks