Custom integration for showing real-time departures from a specified bus/tram stop

Hi all,
I am new to HA and I am trying to create my first custom integration (I know that may be a bit much for starters, but I could not find anything ready-made that fulfils my needs).

I am trying to figure out how to show a bus stop schedule with real time data on one of my dashboards. I found the GTFS data source for my city, but all of the existing integrations that I found require me to specify a stop AND a route to display. I want do display all the arrivals/departures from a specified stop, so that would mean all the routes that go through there.

How could that be achieved in HA?
I want to add that I am well familiar with programming in python/other langs and the surrounding stuff, like using REST APIs etc., but not that familiar with the HA ecosystem and the different components of it.

The other integrations that I mentioned are this and this.

Okay, I got help about this on HA Discord.
I can just create a custom integration with a sensor, stuff all the data into the sensor attributes, and then use the attributes in a custom HACS card to display the info in a nice UI