Donations is a good way of funding, hopefully in the future we can get donation funding from public institutions for FOSS applications!

My own vector map style is using #openFreeMap tiles, which follows the #openMapTiles schema. I hope that some of the issues in that (the schema) can be fixed along the way, so that we have a fully open, good source of tiles.
Look at my profile for screenshots, it is not currently available for browsing anywhere, but I try to make a rich, light style, based on osm-bright, but with lots of stuff added that was not in osm-bright, and even some not in the default omt style.

And yes, services cost money, but that’s no excuse to make something proprietary. Prāv is a great example - it’s libre licensed, and is funded by donations (moving to subscriptions in the near future). For another method, see https://contrapunctus.codeberg.page/blog/free-software-funding-2.html

I like cartes.app. Looks like they use maptiler tiles, which are not fully open, but it works resonably well. There is also https://osmapp.org, in case you didn't know

The magic maps android app shows traffic information, but that is also not fully open - freemium business model. But developing and providing a complex app does cost money