In the mentioned Proton calendar, you can share your calendars, but NOT when using the free plan.
So I would say - if you’re already using Proton “suite”, you can give it a go. But if you don’t then I don’t think it makes sense to pay just for their calendar feature. It’s pretty basic (which is sufficient for me, but not for everyone)
We do have a local meteorological agency, but their webpage and app are not good. It’s pretty unintuitive and it takes a lot of clicking to get the info you want. That’s why I always used something different.