I use Citymapper for this; have for years (https://citymapper.com/). It does exactly what you're asking for. I too am surprised that Google hasn't eaten their lunch by baking this into Google Maps.
Not sure about their scooter coverage though; I don't use it for that.
actually it's famous for the second one
The cool thing is that for Sydney, the same APIs are available to the public: https://opendata.transport.nsw.gov.au/dataset/public-transpo...