@Remus2
For my own edification, how much of that tradition survives today in Latvia, and in what form?
Generally, I would say not much, but still it's alive and well. Depends on what you're asking.
The exact little ritualistic willow-catkin spanking in practice could range from being enacted by next to nobody to hardly anyone and then on rare occasions, while I believe many if not most nationals would be aware of it in principle and could list it if asked about traditional stuff to be done that day for long enough, if not for anything else, then national traditions being part of national literature curriculum in school. But it's not something in the spotlight, or being strongly felt about or enforced by most families, nor being something seen as important or characteristic for that day. All the affair with the colored eggs take much of the spotlight, and the swing comes close second; both much more important and attractive activities all day long. So even in the day's context within tradition, it's a footnote.
For the national tradition as such, the spirit is strong, the knowledge at best spotty, and the practice is minimal and episodic. Still, as the "last pagans of Europe" we feel the self-appointed mission to be keepers of the tradition that once had been huge and widespread in central and east Europe before christianity.
It's not paganism by exact definition either, although that depends on the interpretation. In version I personally subscribe for, word "God" is never used in plural. A pantheon of Nordic or even Greek template can be constructed if one insists, but I personally believe it's rather a late reinterpretation -- as part of the nineteenth century reinvention of the language and mythology in parallel with discovery and documentation and the romanticism trend.
The traditional God-iness or Godkeeping is in principle extremely tolerant unobtrusive and flexible. The belief is that stupidity, not knowing world's principles, only brings self-harming in the first place, so, while you are free to believe whatever nonsense you have come up with it's your responsibility to educate yourself. There exists a movement that tries to build something resembling an organized religion out of it, but it's a small group and outlier rather than mainstream.
The forest is the church. Everything has, well, a soul. Yes, the tree and the river too. A flower left on the sacred stone is the devotion, the "sacrifice" -- of course after you have asked permission to pluck the flower, yes to the flower herself (well, there's two words: one means flower/sacrifice or as a verb "to sacrifice"/"while blooming" and the other is victim/sacrifice; only the first is normally used in context of traditional God-iness, the second mostly speaking about foreign religions. And nothing of that is important.). The body of over two million songs of mathematical beauty is the equivalent of sacred texts. Some simple words have alternative meanings, including sanskrit collisions that may or may not be incidental. Some of that stuff is indeed believed to be that old there was no difference.
Christianity... there's little to no conflict from our side, taking it broadly. Most Latvians nowadays self identify as Christians even if could have been in church for three occasions in their entire lives: baptism, wedding and funeral. In Soviet times much any couple married triple the same day: in government office, church, and traditional midnight ritual at home. And yes, our Lutheran churches have cocks on the spires instead of cross. And by the way, somewhere in that crosssection the Christmas Tree got invented.
But I'm rambling. To conclude, it's officially unofficial, but in practice may easily be more prevalent in everyday life than the unofficially official Christian church for most of people. Although really they exist on different layers, or if Latvian-ism itself is seen as form of religion, we're officially allowed to practice more than one religion at the same time, at least as long one of them is the ethnic identity.