To add the new route, we must implement it in a few places (since routes are dynamic and configurable).

To seed the route to the database, add an entry here.
https://github.com/EtherealEngine/etherealengine/tree/dev/packages/server-core/src/route/route/route.seed.ts

To configure the route in the default project, add an entry here.
https://github.com/EtherealEngine/etherealengine/tree/dev/packages/projects/default-project/xrengine.config.ts
(Note: when the engine is seeded with npm run dev-reinit, this file will be copied to /packages/projects/projects/default-project, so if you make changes in either of the files linked above, you will need to re-run npm run dev-reinit and npm run dev in order to see the changes affected.

This new route should look like the offline route here:
https://github.com/EtherealEngine/etherealengine/tree/dev/packages/client/src/pages/offline/%5BlocationName%5D.tsx

We have a concept called XRUI, which is what we are slowly migrating all of our UI over. This rasters the DOM elements rendered from the react component tree into a texture that can be presented in 3D (hence it being an XR UI). The implementation of these are quite similar to normal UIs, in that it is rendered with react and jsx, but there is some additional data structures that it sits in. You can see some examples of these here:

https://github.com/EtherealEngine/etherealengine/tree/dev/packages/client-core/src/systems/LoadingUISystem.tsx
https://github.com/EtherealEngine/etherealengine/tree/dev/packages/client-core/src/systems/ui/LoadingDetailView/index.tsx
and
https://github.com/EtherealEngine/etherealengine/tree/dev/packages/client-core/src/systems/WidgetUISystem.ts
https://github.com/EtherealEngine/etherealengine/tree/dev/packages/client-core/src/systems/ui/WidgetMenuView/index.tsx

In terms of what the UI should look like, we want something very simple and minimalist, like the UI panels at our explore page:
https://www.etherealengine.com/explore that look like this.

We have a few default locations, which you can explore locally:
https://localhost:3000/location/default
https://localhost:3000/location/sky-station
https://localhost:3000/location/apartment

Essentially, we want to extend the feathers location service API to include being able to fetch a list of locations.
https://github.com/EtherealEngine/etherealengine/tree/dev/packages/client-core/src/social/services/LocationService.ts
I believe currently this is scoped to only admins having access (via https://github.com/EtherealEngine/etherealengine/tree/dev/packages/client-core/src/admin/services/LocationService.ts)
So we should change the backend service to allow non admins to also have access to get a list of all public locations, (admins should still be able to see all private locations also).
I'd recommend making a new service for this, since the data here will be used for a different purpose than the existing LocationState