Here's a platform that aims to solve this problem:

https://www.projectcallisto.org/

Victims report incidents, an their info is not shared at the time of report. Victims can elect to have their reports unsealed if subsequent accusations are made against the same individual. This mirrors the current status quo, where it's less common for victims to speak out if there are no other cases to corroborate, but makes discovery of other cases more feasible.

It's being rolled out specifically in the context of college sexual assault, but I imagine the approach could work elsewhere too.

Write an anonymous blog about it on Medium or whatever and submit it to HN, you'll get views. You'll persuade or not persuade some people in the blog's truth no matter what you say from confirmation bias alone (e.g. rise in sexism in tech vs. rise in hoax charges). Some people will be more persuaded if you use your real name, for others it doesn't matter. Some people will be more persuaded if you give actual specifics about what was said and done (I'm one of those -- "harassment" is very broad, "groping" might be too, you need to either define your terms or state physically what happened, because you'd think we would all agree on what "grope" means but there are videos you can find of women screaming "help, he's raping me!" when it's just a cop using force to arrest her), but on the other hand too specific and people might find it literally incredible that someone actually grabbed you by the pussy without a tape of the person admitting as much.

There isn't really, because the moment you reveal enough actual details that it's possible to identify you, you also open yourself up for subtle forms of retaliation.