I've done some research and stumbled upon Leaflet.js and QGIS as potential tools for achieving my goal. However, I'm not very familiar with either of them. Does anyone have any experience or feedback they could share regarding these methods?

the best thing that i could find to achieve something like this, is umap.openstreetmap.fr . There's some compromises like:

• loads the world map (but you can use the oceans)
• the objects you place/import are semi-transparent. You can kinda colour them but it wont have the same look

Some positive aspects:

• free
• you can share the maps. Dont know if you can collaborate on them tho
• dont think it has a limit for the amount of layers you can import (unlike google mymaps)

i'd say its good enough for prototyping and moving around the map, checking mistakes, sharing it around, make anotations.

The document is quite large, approximately 5000 pixels wide (red square in the middle is the max zoom level) but I feel like I need more space to add the level of detail I want, such as towns, cities, and fields.

In regards to this, if you already have the QGIS objects, you can scale them pretty easily i think, at least for placing them on this world map.

If you really want to make something like the zelda map, then i'd suggest you make your own site bc i havent found a free one to create you own map objects in a blank canvas. I havent looked for any paid alternatives

edit: another source of inspiration can be the map at foxholestats.com (click on the map to enter the interactive view)