GEO Json Editor: http://geojson.io/#map=2/31.1/31.1
Indoor Mapping Data Format (useful: https://www.linkedin.com/pulse/indoor-mapping-your-venue-new-imdf-standard-tiana-warner/ and study on incompatibilities: https://opengeospatialdata.springeropen.com/articles/10.1186/s40965-019-0063-1 and YC strand is funny https://news.ycombinator.com/item?id=24763023 )
Feb 2021 is the big moment https://appleinsider.com/articles/21/02/24/apples-indoor-mapping-format-adopted-as-community-standard
https://www.raywenderlich.com/12690970-indoor-maps-on-ios-advanced-mapkit
https://duckduckgo.com/?q=lax&t=h_&ia=about&iaxm=about
https://appleinsider.com/articles/13/03/24/apple-buys-indoor-gps-company-wifislam-for-20m
Wayfinding Solutions for Hospitals
https://maps.google.com/help/maps/indoormaps/casestudies.html