I love citymapper, however it only covers a limited number of urban areas, is UK based and most importantly got bought by Via Transportation in 2023 (US based).
It seems like many city/regional operators have their own apps, this might be an option for you ?
You might also want to have a look at the apps that use transitous.org (listed on their homepage). Amongst them is cartes.app, which is a really exciting open source gmaps alternative wannabe, hosted in France (see cartes.app/roadmap for more technical details). Although it’s still a wip, they’ve made great strides recently and I’ve started using it to replace some of GMaps’ use cases. The only issue is, errrr, there’s no English interface for now :) It’s still a small team, so they’re keeping internationalisation for later.












What about Dark Math’s Tangerine Antarctic ?