Not weird. I keep my phone on airplane mode unless I'm actively making a phone call, for privacy reasons (here in the USA, cell tower data is sold to anyone with money through data brokers). Using a mobile map app (Google, Bing, HereWeGo, etc.) with location services on would be pretty bad for privacy. I like the fact that CoMaps works even when the location service is off (unless I don't know where I am and I need the current location) and the airplane mode is on.

The web interface is the official OSM at https://openstreetmap.org/ - it works well in both desktop and mobile browsers. The CoMaps app is mainly useful to those without mobile data plans or prefer not to, as it stores the maps offline/on-device.

I think processing GTFS data offline and on-device might be really challenging. There's OpenTripPlanner, which is web-based and can be self-hosted on a VPS (an example).

It still crashes when I try to get a walking direction... it does not happen with driving or bicycling directions, just walking.

And of course, even if they did, tech savvy kids can just self-host an instance on their own computer.

Now the USA is officially an international pariah.