You might not care about Germany or Japan, but there's plenty of FOSS developers there that need to have working licenses. Is it possible that those jurisdictions might change their mind? Yes, but it's also unlikely. Copyright harmonization has been entirely focused on the needs of the proprietary world[0]. Thus, if your goal is to effectively disclaim copyright, you need to choose legal actions that fit within the mold that the proprietary world has forced upon us. If the proprietary world does not care about artists being allowed to dedicate works to the public domain, then you won't be able to do so internationally.
[0] e.g.
- Very long copyright terms - Unwaivable moral rights for (copyright-wielding) artists - Strong domestic enforcement for international copyright holders - Upper bounds on exceptions to copyright - Forcing everyone to adopt DMCA 1201 - Making copyright exempt from normal democratic process
> End result is the same without the uncertainty.
You fell for the boomer FUD.