I was recently recommended https://api.transitous.org (it's a webapp despite the domain). It can do things like "someone can pick me up on the far side and I don't mind walking 30 minutes at the start at 6 km/h, what's the optimal route to take?"

Revolutionary! Finally I don't have to look on a map to find all stations in walking/cycling/driving distance and then route to/from every possible combination of start and end station manually to see what busses and trains run there. And repeat the process with each schedule change in each involved country. Every other transport app that I know of will try to keep you within a few hundred metres of a bus stop or train station at all times and say "there exists no route" before telling you to cycle 10 minutes or from which station you have the shortest remaining distance by taxi or whatever

There is actually work being done to integrate exactly this API into Comaps! Although it will certainly take some more time, especially until these more niche routing features are available