Hi Julia,
Thanks for your note. I’m not familiar with OSM, so it’s hard for me to gauge. With the right skills, resources, and/or creativity, almost anything is possible with our plugin :D. But I’m not familiar with other users trying to change the map that’s used. I suspect it would be pretty complicated, particularly if you were using Events Calendar PRO which includes more uses of the map.
The best way to gauge this is to download our free core plugin, The Events Calendar, and see if you can get OSM working with that. You’ll want to check out our documentation to get started. If you can get that working as needed, you might consider going PRO. But please note that because this is way outside the design of our calendar, we wouldn’t be able to provide any support for your OSM implementation. Please let me know if you have any further questions.
Best,
Leah